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NOV  37 19^ 


Arrt  -to  .  . 




Sir  William  Bragg,  K.B.E.,  D.Sc..f.r.s. 
Concerning  the  Nature  of  Things 

Richard  Swann  Lull,  Ph.D.,  D.Sc. 

Professor  of  Paleontology,  Y»Ic  University;  Director, 
Peabody  Museum;  Fellow  of  the  American  Academy 
of  Arts  and  Sciences,  etc. 

The  Ways  of  Life 

George  A.  Dorsey,  ll.d.,  Ph.D. 

Formerly  Curator  of  Anthropology,  Field  Museum, 
and  Associate  Professor  of  Anthropology,  University 
of  Chicago. 

Why  We  Behave  Like  Human  Beings 

Bertrand  Russell 

The  A  B  C  of  Relativity 

Edwin  Grant  Conklin,  Ph.D.,  Sc.D. 

Professor  of  Bio lo5y,  Princeton  University ;  Fellow  of 
the  American  Academy  of  Arts  and  Sciences,  etc. 

The  Revolt  Against  Darwinism 

Charles  Singer,  D.Litt.,  M.D.,  F.R.C.P.,  f.s.a. 

Late  University  Lecturer  in  History  of  Biological 
Sciences.  Oxford. 

History  of  Science 





George  A.  Dorsey,  Ph.D.,  LL.D 

Formerly  Associate  Professor  of  Anthropology 
University  of  ChicagOy  and 
Curator  of  Anthropology 
Field  Museum  of  Natural  History 

Harper  &  Brothers 

New  York  and  London 


Copyright,  1925,  by 
Harper  &  Brothers 
Printed  in  the  U.  S.  A. 

First  Edition 



Father  and  Mother 

Digitized  by  the  Internet  Archive 
in  2014 


Preface   xi 

Chapter  I.   The  Individual  Life  Cycle  and  the  Human  Race 

1.  The  Egg  of  Life   1 

2.  The  Embryonic  Germ-Layers    3 

3.  The  Fetal  Gill-Clefts   6 

4.  The  Fetal  Nervous  System   9 

5.  The  Fetal  Skin  and  Sense  Organs   12 

6.  The  Fetal  Urogenital  System   16 

7.  The  Fetal  Alimentary  Canal   19 

8.  Twins  and  Monsters   22 

9.  Walking  Museums  of  Anatomy   25 

10.  The  Maturing  Body   32 

IL  The  Adult  and  Senile  Body   34 

12.  The  Human  Race   38 

13.  The  Two  Great  Divisions  of  Man   44 

14.  Fossil  Man   47 

15.  Our  Next-of-Kin-Living   49 

16.  Changing  Limbs   53 

17.  The  Race  to  Be  Human  .   56 

Chapter  H.   The  Evolution  of  the  Earth,  Life,  and  Sex 

1.  Life's  Genealogic  Timetable   60 

2.  The  Hand  That  Rocks  the  Cradle  

3.  Experiments  in  Brains   69 

4.  New  Styles  in  Eggs  and  Incubators   71 

5.  Our  Indebtedness  to  Fish   73 

6.  Back  to  the  Lifeless  Earth   77 

7.  The  Start  from  the  Sun   80 

8.  The  L  M  N's  of  Nature   82 

9.  The  Fitness  of  Water  and  Carbon  Dioxide  ......  86 

10.  The  Evolution  of  the  Organic                      .  v  .  U  .  92 



11.  Darwin  and  Natural  Selection   97 

12.  Lamarck  and  Acquired  Characters   102 

13.  The  Nature  and  Evolution  of  Sex   105 

14.  The  Colored  Bodies  of  the  Egg   110 

15.  The  Great  Game  of  Heredity   112 

16.  Eugenics,  or  Being  Well  Bred   116 

Chapter  III.   The  Processes  of  Living  and  the 
Germs  of  Disease 

1.  Life  Is  Change  and  Requires  Energy   120 

2.  The  Body  is  a  Living  Machine   123 

3.  It  Requires  Calories   127 

4.  Why  We  Must  Digest  Food   130 

5.  The  Digestive  System   133 

6.  Our  Daily  Bread  and  Water   137 

7.  Seeing  Food  Through  the  Canal   146 

8.  How  Food  is  Absorbed   154 

9.  The  Flesh  Is  in  the  Blood   159 

10.  How  the  "Flesh"  Is  Transported   164 

11.  Giving  the  Blood  the  Air   167 

12.  The  Great  Blood  Purifier   170 

13.  The  Red  Blood-Cells   173 

14.  The  Body  Thermostat   177 

15.  The  Role  of  the  Duct  Glands   183 

16.  The  "Little  Fleas"   186 

17.  The  Deadly  Germs   194 

Chapter  IV.   The  Endocrine  Glands  and  the  Causes 
of  Death 

1.  Endocrine  Glands  and  Hormones   201 

2.  The  Thyroid  Gland    204 

3.  The  Parathyroid  and  Thymus  Glands   206 

4.  The  Adrenal  Glands   208 

5.  The  Emergency  Functions  of  the  Adrenals   212 

6.  The  Pituitary  and  Pineal  Glands   215 

7.  The  Pancreas— and  Other  "Sweetbreads"   219 

8.  Introducing  the  Gonads   221 

9.  The  Dual  Role  of  the  Gonads   224 

10.  The  Female  Gonads   226 

U.  The  Male  Gonads   229 



12.  Secondary  Sexual  Characters   232 

13.  The  More  "Human"  Sex   235 

14.  Endocrine  Facts  and  Fancies   238 

15.  The  Individual  That  Is  Regulated   240 

16.  "How  Can  a  Man  Be  Born  When  He  Is  Old?"   243 

17.  One  Good  Defect  Deserves  Another   248 

18.  The  Parts  That  Wear  Out  First   251 

19.  The  Best  Life  Insurance   254 

20.  Our  Total  Mileage   257 

Chapter  V.   The  Integrating  Organ  and  Mechanism 
OF  Adjustment 

1.  The  Old  and  the  New  Psychology   263 

2.  The  Impulse  to  Live   266 

3.  Samples  of  Low  Life  Behavior   268 

4.  The  Animal  "Mind"   270 

5.  The  Excitability  of  Living  Matter   274 

6.  The  Nature  of  the  Reflex  Arc   278 

7.  The  "All-or-None"  Conductors   281 

8.  Reflex  Action   284 

9.  The  Nature  of  Nerves   287 

10.  The  World  as  Stimulus   291 

11.  Receptors  of  Sights  and  Sounds   294 

12.  Receptors  of  Chemical  Stimuli   298 

13.  Visceral  and  Kinesthetic  Receptors   301 

14.  The  Nervous  System   306 

15.  The  Lower  Centers  of  the  Nervous  System   309 

16.  The  Supreme  Adjustor   312 

17.  The  Pictured  Movements  of  the  Brain   315 

18.  The  Conditioned  Reflex   319 

19.  The  Autonomic  Nervous  System   321 

20.  Cramps  and  Fatigue   .  325 

21.  Mind  and  Consciousness   328 

Chapter  VI.   Acquiring  Human  Behavior 

1.  A  Stork's-eye  View  of  the  Baby   336 

2.  Instinctive  Behavior   340 

3.  Organizing  the  Kinesthetic  Sense   345 

4.  The  Reflex  Basis  of  Habits   349 

5.  Play  and  Imitation   353 



6.  The  Laws  of  Habit  Formation   356 

7.  Instinctive  Emergency  Behavior   359 

8.  The  Fear-Hate  Organization   363 

9.  Childhood's  "Unconscious"  Mind   368 

10.  The  Habit  of  Language   372 

11.  Verbalized  Organization   377 

12.  Adjustment  by  Thought  and  by  Words  .......  381 

13.  Learning  and  Remembering   385 

14.  The  Changing  Situation    388 

15.  Positive  and  Negative  Adaptations   391 

16.  How  Habits  Are  Broken   393 

17.  The  Habit  of  Sleep   396 

18.  "Prophecy  lies  in  ...  'I  have  dreamed' "   400 

19.  Learning  to  Know   403 

20.  Knowing  and  Believing   408 

21.  The  Individuality  of  Response   412 

Chapter  VII.   From  the  Standpoint  of  the  Newer 

1.  Instinctive  Activities   416 

2.  The  Hunger  Complex   420 

3.  The  Complex  Appetite   424 

4.  The  Sex's  Complex    427 

5.  Love's  Coming-of-Age   431 

6.  Bisexual  Behavior   435 

7.  Conditioning  the  Sex  Complex   438 

8.  Marriage  Behavior   441 

9.  Freud's  Devil  and  Other  Psychoses   447 

10.  Fake  Psychology    452 

11.  Reading  the  Mind   455 

12.  Measuring  Intelligence   458 

13.  Character  and  Personality   461 

14.  The  Ideal  in  Human  Behavior   464 

15.  Socially  Useful  Behavior   471 

16.  The  Goal  of  Creative  Evolution   477 

Bibliography  485 

Index  489 



TTUMAN  beings  are  the  most  interesting  objects  on  earth, 
and  to  know  themselves  and  get  along  with  one  another 
is  their  most  important  business.  That  business  drags 
because  they  do  not  know  where  they  come  from,  how 
they  get  here,  what  they  bring  with  them,  what  they  do  with 
it,  and  what  they  could  do  if  they  stopped  quarreling  among 
themselves  and  used  their  brains  to  solve  their  common 
problems.  It  will  speed  up  when  the  raw  materials  of  human 
nature  and  the  possibilities  of  intelligent  behavior  are  more 
generally  understood.  The  facts  for  such  an  understanding 
are  known,  but  they  belong  to  several  sciences  and  are  scat- 
tered through  many  libraries.  To  pick  them  out,  put  them  in 
order,  and  make  them  tell  a  complete  and  up-to-date  story 
that  can  be  held  in  one  hand  and  read  without  a  dictionary 
is  the  object  of  Why  We  Behave  Like  Human  Beings. 

"Complete"  is  a  large  word  and  must  be  taken  with  a  grain 
of  salt.  Nothing  is  really  complete  in  this  world  of  ceaseless 
change  and  expanding  horizon.  The  earth  itself  is  not  the 
earth  it  used  to  be  when  I  first  went  to  school.  Man's  story 
will  be  complete  when  there  is  no  human  being  left  to  tell 
the  tale.  Keibel  and  Mall's  Human  Embryology,  with  1,600 
pages,  is  more  complete  than  Minot's,  with  only  800. 
Quain's  Human  Anatomy,  with  2,000  pages,  is  more  complete 
than  the  average  textbook  of  anatomy,  with  only  1,000. 
This  is  not  a  textbook;  the  changing  human  body,  from  a 
rejuvenated  ovum  to  senile  decay,  and  its  origin  from 
primordial  protoplasm,  are  part  of  this  story. 

Nor  is  "up-to-date"  to  be  taken  too  literally.  Science  moves 
fast  these  days.    I  may  state  that  the  hormone  of  a  certain 



gland  is  "not  yet  known";  Professor  John  Abel  may  have 
isolated  it  yesterday  and  announce  the  fact  next  year.  When 
I  studied  anatomy  under  Thomas  Dwight — ^to  whom  I  owe 
much — I  was  told  nothing  about  a  certain  little  gland  in  our 
throat  without  which  we  cannot  live.  The  activating  principle 
of  that  gland  has  been  discovered,  and  the  secretion  of  an- 
other vital  gland  has  been  isolated,  since  I  wrote  the  first 
word  of  this  book.  No  one  had  heard  of  a  vitamin  a  few 
years  ago,  nor  had  any  vitamin  been  isolated  when  I  began 
this  book;  one,  and  possibly  two,  has  since  been  isolated. 

By  "complete"  I  mean  comprehensive.  This  is  the  most 
comprehensive  account  of  human  beings  that  I  know  of. 
It  is  as  up-to-date  as  I  can  make  it.  It  moves  as  fast  as  I 
can  make  it,  and  avoids  blind  alleys  which  lead  nowhere. 
It  does  touch  many  problems  not  yet  solved  or  only  partially 
guessed  at;  its  handling  of  such  problems  is  as  sound  and 
sane  as  I  can  make  it  with  the  help  of  many  friends.  This 
does  not  commit  them  for  my  errors  of  omission  and  com- 
mission, nor  lessen  my  responsibility  for  statements  of  fact 
or  inferences  from  facts  and  hypotheses — nor  signify  that 
they  approve  an  anthropologist's  use  of  their  materials  for 
his  story. 

The  paleontologist,  for  example,  claims  fossils.  But  when 
he  finds  a  skull  which  he  says  belonged  to  an  ape-man  or 
to  a  man-ape,  that  skull  belongs  to  me  also;  when  he  finds  a 
set  of  dinosaur  eggs,  I  am  not  interested:  there  are  no  dino- 
saurs in  our  family  album.  The  bacteriologist  and  a  dozen 
other  'ologists,  as  well  as  the  family  doctor  and  dentist,  deal 
in  bacteria;  as  do  I  also,  in  setting  forth  the  role  these 
amazing  little  imps  have  played  in  organic  evolution  and  in 
the  life  and  death  of  human  beings.  The  physiologist — and 
presumably  every  scientist — is  interested  in  the  news  about 
the  endocrine  glands.  The  news  is  startling;  but  much  that 
is  not  yet  known  or  is  known  to  be  false  has  been  so  capital- 
ized by  quacks  and  marvelmongers  that  I  have  tried  to  sepa- 
rate the  glands  from  the  grafters.     Different  scientists 



specialize  in  psychic  behavior.  Psychics  and  pseudo-psy- 
chologists exploit  it;  they  too  belong  to  the  story  of  why 
we're  human.  In  short,  my  attitude  is  that  any  science  which 
holds  itself  aloof  from  life  and  nowhere  comes  in  contact 
with  human  beings  is  as  barren  as  a  Vestal  Virgin  and  as  dry 
as  a  prayer  for  rain  for  the  purpose  of  this  book;  but  that 
the  scandalmongers  of  science  who  would  fill  their  lamps  at 
the  expense  of  the  gullible,  and  who  illumine  no  path  of  life 
nor  sustain  any  living  germ,  should  be  illuminated. 

This  book  does  not  presume  to  offer  a  Philosophy  of  Life 
or  suggest  Science  as  a  substitute  for  Religion.  But  as 
philosophy  was  moonshine  until  it  began  to  investigate  the 
elementary  properties  of  matter  and  energy,  so,  I  suspect, 
religion  will  be  subject  to  quackery  and  hypocrisy  until 
humanity  itself  becomes  more  humane  than  human  nature 
and  religion  itself  ceases  worrying  about  heaven  and  hell 
and  devotes  its  energies  to  making  this  earth  a  paradise. 
*  Nor,  in  ascribing  "mind"  to  a  specific  irritability  of  proto- 
plasm and  human  actions  to  definite  forms  of  energy,  does 
this  book  pretend  to  "resolve  life."  Life  is  more  easily 
destroyed  than  resolved,  or  even  defined.  Nobody  knows 
what  life  is.  Much  is  known  of  living  processes.  Of  the 
electric  change  accompanying  irritability,  of  the  action  of 
X-rays  on  living  protoplasm  and  of  heat,  light,  and  sound 
waves  on  sensitive  human  bodies,  not  much  is  yet  known. 
But  those  energies  and  the  living  mechanisms  which  react 
to  their  stimuli  can  be  investigated.  The  few  crumbs  that 
science  can  offer  are  more  nourishing  than  the  no-bread 
of  speculation  which  works  without  oxygen,  ignores  carbon- 
compounds,  and  defies  the  lightning. 

Parts  of  the  chapter  on  the  "Processes  of  Living"  will  be 
difficult  for  those  unfamiliar  with  H2O  and  CO2.  Some  may 
even  sympathize  with  the  French  Republic  of  1794  for  having 
beheaded  the  man  who  said  that  life  is  a  chemical  function. 
But  Lavoisier  was  right:  life  is  a  chemical  function — and 



living  actions  are  largely  concerned  with  conjugating  the 
verb  to  eat.  Without  some  idea  of  oxidation  processes,  of 
the  chemical  structure  of  food,  and  of  the  chemical  reactions 
in  digestion,  visceral  behavior  is  a  blank.  And  without  some 
understanding  of  visceral  behavior,  psychic  behavior  is  up 
in  the  air.  Life  became  a  science  when  interest  shifted 
from  the  dissection  of  dead  bodies  to  the  study  of  action  in 
living  beings  and  the  nature  of  the  environment  they  live  in. 

To  those  scientists  who  have  given  me  of  their  time  and 
learning  I  am  profoundly  indebted  and  here  offer  my  grate- 
ful thanks:  to  Dr.  W.  I.  Thomas,  who  read  the  entire  MS.; 
to  Dr.  Adolph  H.  Schultz,  of  the  Carnegie  Institution  of 
Washington,  Department  of  Embryology,  Johns  Hopkins  Uni- 
versity, who  read  Chapter  I;  to  Professor  Franz  Boas,  of 
Columbia  University,  who  read  parts  of  Chapter  I;  to  Pro- 
fessor George  Grant  MacCurdy,  of  Yale  University,  who 
read  parts  of  Chapters  I  and  II;  to  Professor  W.  E.  Castle, 
of  Harvard  University,  who  read  Chapter  II;  to  Professor 
Richard  Swan  Lull,  of  Yale  University,  who  read  Chapter  II 
and  parts  of  Chapter  I;  to  Professor  Walter  B.  Cannon,  of 
Harvard  University,  who  read  part  of  Chapter  III;  to  Dr. 
McKeen  Cattell,  of  the  Cornell  University  Medical  School, 
who  read  Chapter  III;  to  Professor  A.  J.  Carlson,  of  the 
University  of  Chicago,  who  read  Chapter  IV;  to  Professor 
C.  Judson  Herrick,  of  the  University  of  Chicago,  who  read 
Chapter  V;  and  to  Dr.  John  B.  Watson,  who  read  Chapters  VI 
and  VII. 

I  am  also  indebted  to  Professor  Carlson  for  the  privilege 
of  examining,  while  in  proof,  his  chapter  on  Organotliera- 
peutics  in  the  Blumer  edition  of  Billings-Forchheimer's 
Therapeusis  of  Internal  Diseases;  and  to  Professor  John  J. 
Abel  of  Johns  Hopkins  University,  Professor  R.  G.  Hoskins 
of  the  Ohio  State  University,  Dr.  C.  R.  Moore  of  the  Univer- 
sity of  Chicago,  and  Dr.  John  B.  Watson,  for  reprints  of 
articles  and  for  valued  suggestions. 



Two  names  I  wish  especially  to  mention:  Professor  Franz 
Boas,  unfailing  source  of  inspiration  to  all  American  an- 
thropologists; my  wife  Sue,  untiring  and  indispensable  ally 
in  all  that  has  gone  into  the  writing  of  this  book. 

George  A.  Dorse y. 

New  York  City,  June  1, 1925. 



eine  Arbeit  wird  eigentlich  nie  fertig" 




1.  The  Egg  of  Life.  2.  The  Embryonic  Germ-Layers.  3.  The  Fetal  Gill- 
Clefts.  4.  The  Fetal  Nervous  System.  5.  The  Fetal  Skin  and  Sense  Organs. 
6.  The  Fetal  Urogenital  System.  7.  The  Fetal  Alimentary  Canal.  8.  Twins 
and  Monsters.  9.  Walking  Museums  of  Anatomy.  10.  The  Maturing  Body. 
77.  The  Adult  and  Senile  Body.  12.  The  Human  Race.  13.  The  Two  Great 
Divisions  of  Man.  14.  Fossil  Man.  15.  Our  Next-of-Kin-Living.  76.  Changing 
Limbs.    77.  The  Race  to  Be  Humane. 


We  know  of  only  three  kinds  of  living  beings:  bacteria, 
plants,  animals.  All  living  beings  have  a  physical  body  or 
structure  made  up  of  a  few  of  the  more  common  chemical 
elements.  This  body  is  called  protoplasm,  the  stuff  of  all 
living  things.  Living  protoplasm  occurs  only  in  units  called 
cells.  Every  living  being  is  or  has  been  a  cell.  Cells  are 
always  small  and  generally  cannot  be  seen  except  under  the 

Many  animals  consist  of  just  one  cell,  and  hence  are 
called  unicellular  organisms.  Yet  that  cell  suffices  for  them 
to  live;  they  eat,  they  excrete,  they  grow,  they  multiply; 
they  obey  all  the  laws  of  living  organisms.  For  living  pur- 
poses they  are  complete.  Higher  animals  have  bodies  of 
many  cells,  and  are  called  Metazoa  to  distinguish  them  from 
the  Protozoa,  or  unicellular  animals. 

We  are  animals  and  belong  to  the  Metazoa  group.  Our 
body  consists  of  about  twenty-six  thousand  billion  cells. 
Each  cell  is  alive  and  must  be  nourished  or  it  dies. 

The  cells  which  make  up  our  body  are  of  diflferent  forms 
and  shapes  and,  except  the  free  floating  cells  carried  by  the 



blood,  are  united  into  different  kinds  of  tissue  to  form  the 
organs  and  systems  of  our  body.  But  a  section  cut  anywhere 
from  the  body — from  bone,  muscle,  eye,  tongue,  skin,  heart — 
would  under  the  microscope  be  seen  to  consist  of  tiny  cells, 
each  a  complete  unit  of  protoplasm. 

Our  body  begins  its  individual  growth  and  development  as 
one  cell,  the  germ-cell  or  fertilized  ovum  (egg).  By  fer- 
tilization, the  ovum,  an  old  cell,  is  stimulated  to  begin  a  new 
life;  it  is  made  young  again.  Being  rejuvenated,  it  can  grow, 
and  grow  old. 

The  germ-cells  (female,  or  ova;  male,  or  spermia)  are 
readily  distinguishable  under  the  microscope.  Ova  are  much 
larger  and  less  active  than  spermia.  The  latter  are  very 
active,  and  propel  themselves  by  a  whip-lash  tail.  Both  are 
complete  living  organisms  and  in  their  combined  bodies 
carry  immortality.  In  general  features,  size,  structure,  etc., 
human  germ-cells  closely  resemble  those  of  other  mammals. 

The  human  ovum  was  first  discovered  in  1827.  Although 
it  is  the  largest  of  the  cells  in  the  body,  fifty  thousand  could 
be  mailed  across  the  continent  for  a  two-cent  stamp;  one 
hundred  could  ride  on  an  inch-long  spider  web. 

In  both  sexes,  the  germ-cells  mature  normally  only  from 
the  beginning  of  puberty.  The  ova  develop  in  little  pockets 
or  follicles  of  the  ovaries.  There  are  about  70,000  follicles 
at  birth.  By  the  eighth  year  there  are  less  than  40,000;  of 
these  only  about  200  develop  into  true  Graafian  follicles. 
One  of  these,  containing  a  single  ovum,  matures  each  lunar 
month  of  life  between  puberty  and  the  menopause.  It  es- 
capes through  the  ruptured  wall  of  the  ovary  and  enters  the 
Fallopian  tube,  presumably  two  weeks  before  the  onset  of 
menstruation.  For  each  mature  ovum  thus  released  each 
lunar  month,  the  male  develops  about  850,000,000,000 

One  spermium  only  enters  into  the  body  of  the  matured 
ovum,  leaving  its  tail  outside.  The  ovum  is  now  fertilized. 
It  divides  into  two  cells;  these  two  divide  and  become  four, 



etc.  In  nine  months,  one  fertilized  ovum  has  grown  five 
million  per  cent  and  increased  in  volume  one  billion  times; 
by  maturity  it  will  have  increased  in  volume  fifteen  billion 

After  the  fertilized  ovum  has  by  division  become  many 
thousands,  certain  cells  under  the  microscope  may  be  dis- 
tinguished from  the  others.  These  are  to  become  the  germ- 
cells  of  new  individuals,  tiny  sparks  of  immortality,  endowed 
with  the  capacity  to  hand  life  on  to  the  next  generation. 

The  other  cells  of  the  tiny  embryo  are  called  soma,  or 
body  cells.  They  also  grow  and  multiply  by  division,  and 
assume  special  shapes  to  fit  them  to  form  the  tissues  and 
organs  of  the  body — nerves,  eyes,  bone,  teeth,  heart,  muscle, 
blood,  etc.  Having  specialized  or  become  differentiated, 
they  cannot  unite  with  other  cells  to  start  new  lives — they  are 
not  germ-cells. 


We  hear  much  of  adaptations.  Every  living  animal  is 
"adapted"  or  it  could  not  live.  What  it  is  adapted  to  and 
what  it  adapts  itself  with  depend  on  the  animal  and  the 
stage  of  its  development.  The  tiny  germ-cell  in  the  hen's 
egg  is  adapted  to  an  environment  of  yolk  and  albumin.  It 
draws  on  these  for  its  nourishment.  The  human  ovum  has 
no  such  store  of  food  to  draw  upon.  It  is  adapted  to  a 
different  environment.  For  280  days  it  is  to  live  the  life  of 
a  true  parasite.  It  must  therefore  attach  itself  to  a  living 
wall,  from  which  it  can  derive  its  supplies  for  living  and 
for  growth.  These  early  adaptations  of  the  human  ovum  are 
of  great  interest. 

But  the  interest  will  be  increased  if  we  have  before  us  a 
law  of  biology  which  says  that  individual  development  re- 
hearses or  recapitulates  the  life  history  of  the  species.  This 
means  that  our  individual  prenatal  and  postnatal  growth  up 
to  the  time  of  adolescence  is  a  resume  of  the  evolution  of  the 



human  race.  It  does  not  mean  that  at  one  stage  of  develop- 
ment the  fetus  is  a  fish,  or  a  reptile;  it  does  say  that  the 
ovum  develops  along  the  road  our  ancestors  traveled  in 
becoming  human. 

We  begin  our  individual  existence  as  a  protozoon  or  single- 
celled  animal;  not  until  the  end  of  the  third  month  has  the 
fetus  the  essential  parts  of  a  fairly  complete  human  being. 
During  the  last  six  months  the  fetus  grows  more  human;  the 
parts  begin  to  mature,  and  for  years  after  birth  keep  on 

The  embryo  begins  at  once  to  develop  from  its  own  body 
the  two  fetal  membranes  or  envelopes.  The  inner  one,  or 
amnion  (lamb),  fills  with  a  pint  or  more  of  water.  In  this 
the  embryo  floats,  and  consequently  any  pressure  to  which 
it  is  subjected  becomes  more  evenly  distributed.  By  a  special 
growth  called  placenta  (cake,  because  of  its  shape)  of  the 
outer  membrane  or  chorion  (skin),  the  embryo  attaches  itself 
to  the  wall  of  the  uterus. 

Through  this  placenta  the  parasite  embryo  derives  food 
and  oxygen.  But  it  develops  its  own  blood  and  its  own, 
circulatory  and  digestive  systems:  they  are  at  all  times  quite 
distinct  from  its  host's.  She  supplies  what  the  chick  embryo 
receives  from  the  hen  egg:  support,  protection,  water,  food, 
fuel,  oxygen. 

Both  fetal  membranes  and  placenta  follow  the  child  at 
birth.  The  child  is  freed  from  the  placenta  by  severing  its 
umbilical  cord ;  our  navel  is  the  scar. 

In  other  mammals  these  membranes  are  not  formed  so 
early,  but  the  upright  gait  of  man  seems  to  put  more  strain 
on  the  abdominal  viscera  and  presumably  subjects  the  embryo 
to  greater  pressure.  It  needs  all  the  protection  it  can  get, 
hence  this  marvelous  intrauterine  adaptation  to  the  upright 
posture.  Anthropoid  apes  have  the  human  type  of  uterus  and 
a  near-upright  gait;  their  fetal  membranes  are  also  formed 
earlier  than  in  other  mammals. 

To  return  to  the  embryo  proper.    The  ovum  divides,  tlie 



two  daughter-cells  divide.  Four,  eight,  sixteen,  thirty-two, 
etc.  As  a  result  of  this  rapid  division,  multiplication,  and 
growth,  the  embryo  passes  through  certain  definite  stages  of 
development.  Much  is  still  conjecture.  For  this  reason: 
The  earliest  stages  of  embryonic  development  of  fishes,  am- 
phibians, birds,  and  of  such  domesticated  mammals  as  the 
guinea-pig,  rabbit,  sheep,  and  pig  are  known,  and  much  may 
be  inferred  as  to  the  course  of  development  of  the  human 
embryo  from  what  is  known  to  take  place  in  these  animals. 
But  no  one  has  yet  seen  a  fertilized  human  ovum,  nor  has 
anyone  yet  seen  a  human  embryo  that  had  not  already  had 
ten  days'  growth — and  it  measured  about  one  one-hundredth 
of  an  inch  in  length.  Even  of  the  second  week  of  human 
development  almost  nothing  is  definitely  known,  and  of  em- 
bryos of  the  third  week  the  Carnegie  Laboratory  of  Embry- 
ology has  been  able  to  assemble  only  fourteen  specimens. 
What  actually  goes  on,  then,  during  the  first  eighteen  days  of 
man's  intrauterine  existence  can  as  yet  only  be  inferred  from 
known  facts  of  lower  mammalian  embryonic  development. 

First  of  the  hypothetical  stages  is  the  morula  (little  mul- 
berry) :  the  embryo  is  a  minute  cluster  of  cells.  Next  is  the 
blastula  stage,  or  blastoderm  (germ-skin) ;  the  embryo  is 
supposed  to  form  a  hollow  sphere.  This  caves  in  on  one  side, 
forming  a  U-shaped  affair,  and  represents  the  gastrula 
(stomach)  stage.  By  this  infolding,  certain  cells  which  were 
on  the  outside  now  lie  inside  the  body;  the  embryo  consists 
of  two  layers.  By  further  infoldings,  there  is  an  additional 
layer  between  these  two.  Thus  we  have  the  famous  and 
important  germ-layers:  the  outer  or  ectoderm;  the  inner  or 
endoderm;  the  middle  or  mesoderm. 

Each  germ-layer  gives  rise  to  certain  organs  and  systems, 
a  fact  of  far-reaching  consequence  in  medicine  and  hygiene 
and  in  an  understanding  of  our  body.  The  three  layers  and 
their  derived  structures  are: 

L  Ectoderm:  skin  and  skin  accessories;  entire  nervous 



system;  special  sense  organs;  pineal  gland  and  part  of  the 
pituitary  and  adrenal  glands. 

II.  Endoderm:  alimentary  canal  and  appendages;  thy- 
roid and  thymus  glands ;  larynx,  trachea,  and  lungs. 

III.  Mesoderm:  voluntary  or  skeletal  muscles;  urogenital 
system  and  sex  glands;  part  of  the  adrenal  glands. 

In  addition  to  these  three  layers,  a  particular  type  of  tissue 
develops,  chiefly  from  the  mesoderm.  Its  cells  are  branched 
and  form  a  network  of  connective  tissue.  From  it  are  de- 
rived the  heart,  blood,  blood  vessels,  and  lymphatic  system; 
skeleton ;  and  visceral  or  involuntary  muscles. 

All  one-cell  animals  consist  of  an  outside  and  "insides." 
Through  their  outside  membrane  or  cell  wall  they  keep  in 
touch  with  the  world.  Our  keep-in-touch-with-the-world 
mechanisms  (skin,  hair,  nails,  all  skin-glands  and  organs, 
lining  of  mouth,  enamel  of  teeth,  special  sense  organs,  and 
entire  nervous  system)  are  all  derived  from  the  outside  cells 
of  the  original  hollow  body  when  it  caved  in  to  bury  certain 
cells  inside  the  body.  From  those  inside  cells  we  develop 
"insides" — food  and  air  canals.  Muscles  and  skeleton, 
blood,  sex  organs,  etc.,  did  not  appear  until  animal  life  had 
made  much  progress  in  evolution. 

During  our  early  prenatal  days  we  live  fast;  we  can  be 
certain  of  that.   In  a  few  days  we  have  developed  structures 
^that  were  evolved  only  after  tens  of  millions  of  years.  , 


Within  two  weeks  the  embryo  has  become  a  minute  plate- 
like structure  with  a  streak  across  it.  By  the  third  week  this 
streak  opens  into  the  plate  at  both  ends.  One  opening 
becomes  the  mouth.  The  cavity  within  the  embryo  will 
divide  and  become  the  thoracic  and  abdominal  cavities. 

Meanwhile,  a  series  of  lines  appear,  dividing  the  plate-like 
embryo  into  segments.  Segmented  animals,  such  as  worms 
and  insects,  retain  these  segments;  as  do  fishes  in  muscles, 



ribs,  and  vertebrae;  as  do  we  in  our  ribs,  vertebrae,  and  the 
muscles  between  the  ribs.  Our  floating  ribs  are  simply  in- 
complete ribs,  but  we  have  vestiges  of  ribs  all  the  way  down 
our  spine.  Those  below  the  chest  fuse  with  outgrowths 
from  die  vertebrae  and  are  called  lateral  processes. 

The  vast  majority  of  animals  have  no  backbone,  and  are 
called  Invertebrates.  One  of  the  greatest  steps  in  evolution 
was  a  backbone  or  vertebral  column.  Three  types  were  tried 
out  before  Vertebrates  developed  a  true  backbone.  All  three 
types  or  stages  appear  in  the  developing  human  embryo.  The 
notochord  or  permanent  body  axis  of  the  lowest  fishes  appears 
early;  later  it  is  obliterated  by  the  bodies  of  the  vertebrae, 
but  traces  of  the  notochord  may  persist  and  lead  to  tumors 
in  adult  life.  Our  bony  vertebrae  proper  are  preceded  by 
cartilage,  the  only  backbone  sharks  have.  This  is  replaced 
by  bone. 

Our  skull  and  limb  bones  also  begin  as  cartilage — and  in 
some  fishes  the  skull  remains  cartilage.  Much  of  our  long 
bones  and  skull  is  still  cartilage  at  birth;  hence  the  pliancy 
of  the  new  horn's  head. 

Shark  embryos  have  five  gill-arches  with  openings,  or  gill- 
clefts,  between,  and  two  branchial  arches  from  which  the 
shark  forms  its  poorly  developed  lower  jaw. 

Most  of  these  arches  and  the  branchial  clefts  between 
appear  at  the  third  week  in  the  human  fetus.  The  way  the 
clefts  disappear  and  the  arches  develop  into  the  extraordi- 
narily complicated  human  throat  is  possibly  the  most 
interesting  and  confused  chapter  in  human  embryology. 

From  one  of  the  two  arches  which  develop  into  jaws  in 
sharks,  the  human  fetus  develops  its  lower  jaw  and  two  of 
the  three  tiny  bones  of  the  inner  ear;  from  the  other  arch,  the 
third  bone  of  the  inner  ear,  the  styloid  process  at  the  base 
of  the  skull,  and  the  cartilage  of  the  external  ear.  The 
hyoid  apparatus  which  supports  our  tongue  develops  also 
from  this  and  from  the  first  gill-arch.    The  second  and  third 



gill-arches  become  the  thyroid  cartilages,  or  Adam's  apple; 
the  fourth,  the  epiglottis;  the  fifth,  the  windpipe  cartilages. 

As  the  human  embryo  will  develop  into  a  lung-breather 
and  will  have  no  need  of  gills,  the  gill-clefts  do  not  break 
through;  after  the  sixth  week  no  outward  trace  of  them 
remains.  But  around  one  end  of  the  first  cleft  the  fetal  ear 
develops;  the  remainder  becomes  the  Eustachian  tube,  or 
passage  from  the  mouth  to  the  tympanic  cavity  of  the  ear. 

The  second  branchial  arch,  from  which  fish  embryos  de- 
velop gill-cover  and  gill  muscles,  is  supplied  by  the  seventh 
cranial  nerve.  This  arch  in  the  human  fetus  is  also  supplied 
by  that  nerve;  it  grows  upward  and  becomes  the  great  nerve 
of  our  face,  supplying  ears,  mouth,  nose,  and  eyes.  An 
amazing  story,  this.  The  nerves  of  our  face  moved  the 
gill-covers  of  our  respiratory  system  when  we  were  fishes. 

Six  branches  of  the  aorta — the  great  artery  from  the 
heart — supply  these  fish-like  arches  of  the  human  fetus. 
The  third  pair  become  part  of  the  two  internal  carotid 
arteries.  The  left  branch  of  the  fourth  pair  forms  the  bend 
of  the  aorta.  Of  the  sixth  pair,  one  part  becomes  the  stem 
of  the  pulmonary  artery;  the  other,  during  fetal  life,  carries 
blood  from  the  pulmonary  artery  to  the  aorta,  thus  permitting 
the  right  ventricle  of  the  heart  to  pump  impure  blood  into 
the  aorta  and  so  to  the  placenta.  At  birth  it  closes;  blood 
from  the  pulmonary  artery  must  now  pass  to  the  lungs. 

Marvelous  adaptation!  Part  of  a  gill-arch  artery  used  for 
placental  circulation  closed  suddenly  to  meet  the  infant's 
cry  for  air!  Henceforth  the  infant  gets  oxygen  from  its  own 
lungs  and  not  from  its  mother's  blood. 

During  fetal  life,  the  third  and  fourth  clefts  become  cov- 
ered by  a  fold  from  the  second  arch.  A  fistula  may  develop 
here — remnant  of  an  enclosed  gill  chamber.  The  middle  ear, 
site  of  the  first  fetal  gill-cleft,  is  more  prone  to  serious 
trouble.  Tags  of  skin  which  may  persist  on  the  side  or  front 
of  our  neck  are  less  serious,  but  none  the  less  echoes  of  our 
gill-clefts,  reminders  of  our  kinship  with  the  finny  tribes. 



At  the  time  the  gill-clefts  are  present  the  human  fetus  has 
a  freely  projecting  tail  and  four  tiny  paddle-like  limbs. 


The  ovum  only  grows  and  develops  if  it  can  come  in  contact 
with  food;  the  cells  remain  alive  only  as  long  as  they  are 
nourished.  This  gives  us  a  clue  to  some  of  the  mechanisms  or 
organ-systems  which  the  human  embryo  must  develop  and 
which  we  must  keep  in  repair  during  life.  Whether  we  are 
a  one-cell  embryo  or  a  new-born  or  an  adult,  we  must  be 
able  to  get  food  and  oxygen  and  distribute  food  and  oxygen 
where  needed.  We  have  such  organ-systems:  digestive,  cir- 
culatory, respiratory,  etc.;  and  a  motor  mechanism  of  bones 
and  muscles. 

A  fundamental  criterion  of  living  protoplasm  is  its  capac- 
ity to  get  excited.  Because  of  this  irritable  nature  it  does 
something — it  reacts  like  a  living  thing.  The  "organ-system," 
or  mechanism  of  reactions,  is  the  nervous  system  in  man 
and  in  all  animals  with  a  nervous  system.  But  just  as  we 
must  infer  that  the  ovum  can  "breathe,"  although  it  has  no 
lungs,  we  must  infer  that  it  can  react,  although  it  has  no 
nervous  system. 

It  is  vitally  important  that  at  every  stage  of  pre-  or  post- 
natal life  the  organism  have  all  the  structure  or  mechanism 
required  for  living  purposes;  it  only  needs  to  make  living 
response  to  living  environment.  The  nervous  system  comes 
to  be  the  visible  mechanism  by  action  in  which  the  organism 
makes  such  vital  responses  to  vital  situations. 

Our  nervous  system  is  the  most  complex  mechanism  in  the 
universe;  certainly  no  other  system  in  our  body  is  to  be 
compared  with  it  in  intricacy  or  in  its  unique  capacity  to 
learn.  Because  of  this  capacity,  the  evolution  of  man  became 
possible  and  we  are  what  we  are.  In  fact,  the  goal  of  evolu- 
tion, as  we  shall  see,  was  always  in  the  direction  of  a  broader 
outlook,  a  greater  capacity  to  anticipate  change  and  weather 



storm.  The  nervous  system  is  the  only  key  evolved  to  unlock 
the  future.  We  shall  pay  due  respect  to  it;  at  this  point  we 
can  only  glance  at  its  structural  development. 

Before  the  embryo  is  a  month  old,  a  depression  or  trough 
appears  on  the  upper  surface  of  the  outer  germ-layer.  It 
deepens.  The  upper  edges  come  together,  forming  the  neural 
tube,  so  called  because  from  it  will  develop  the  nervous 
system.  In  the  third  month  the  tube  expands  at  one  end  into 
three  sacs  or  vesicles;  the  first  and  third  of  these  divide  and 
there  result  five  vesicles  in  all.  The  walls  of  these  hollow 
sacs  will  develop  into  the  brain;  the  sacs  themselves  will  form 
the  ventricles  (little  belly)  of  the  brain. 

The  remainder  of  the  neural  tube  will  become  the  spinal 
cord.  This,  in  the  four-months'  embryo,  is  as  long  as  the 
vertebral  column;  thereafter  the  column  grows  faster  than 
the  cord.  At  birth,  the  cord  proper  reaches  only  to  the  third 
lumbar  vertebrae;  but  from  that  vertebrae  to  the  end  of  the 
column  the  cord  is  represented  by  the  long  terminal  filament. 
This  atavistic  ending  of  the  spinal  cord  is  found  in  mammals 
generally,  and  points  back  to  a  time  in  man's  ancestry  when 
the  cord  extended  the  entire  length  of  the  column. 

The  cells  of  the  neural  tube  send  out  two  processes:  one 
connects  with  a  process  from  another  cell  of  the  central 
system;  the  other  grows  out  toward  the  surface  of  the  body. 
By  birth,  all  parts  of  the  body  are  connected  by  these  proc- 
esses with  central — spinal  cord  and  brain — and  by  the  other 
processes,  all  parts  of  central  are  connected  with  one  another. 
At  birth,  all  the  cells  of  the  nervous  system  are  present. 
The  new-born  will  develop  no  new  brain  cells,  but  structural 
changes  will  take  place  in  the  nerves  which  are  in  control 
of  the  motor  mechanism;  otherwise  the  infant  would  remain 
as  helpless  as  when  born. 

Sometimes  the  bones  of  the  skull  grow  together  prema- 
turely; this  prevents  further  growth  of  the  brain.  Such  a 
brain  is  called  microcephalous  and  vaguely  resembles  the 
brain  of  monkeys. 



Monsters  are  sometimes  delivered  in  which  the  brain  has 
never  developed  beyond  the  first  month  of  fetal  life — ^the 
original  nerve  plate  remains  spread  out  on  the  surface  at 
the  back  of  the  head. 

An  English  shepherd  who  died  at  the  age  of  sixty  was 
normal  except  for  his  very  small  head.  He  had  a  human 
countenance,  but  a  vacant  stare.  He  could  count  his  fingers, 
but  not  his  sheep  or  the  days  of  the  week.  He  could  talk 
simple  sentences.  His  brain  was  one-third  normal  size  and  its 
fissures  were  like  a  fetal  brain  of  seven  months,  but  lower 
in  type  than  that  of  a  chimpanzee.  The  parts  associated  with 
speech  were  of  the  size  and  form  found  in  anthropoid  apes. 
It  was  the  type  of  brain  our  ancestors  had  millions  of  years 

Man's  brain  is  from  two  to  three  times  larger  than  that 
of  the  gorilla,  but,  apart  from  mere  size,  man  and  ape  brains 
are  more  alike  than  are  their  big  toes. 

Brain  weights  vary  enormously.  The  average  for  adult  male 
Europeans  is  about  1,375  grams,  for  females  about  1,235. 
The  brain  of  Turgueneff,  the  Russian  novelist,  weighed  2,012 
grams.  It  is  exceeded  by  that  of  only  two  others ;  one  was  an 
imbecile.  Next  in  weight  come  a  laborer  (1,925  grams)  and 
a  bricklayer  (1,900  grams).  Gambetta's  brain  weighed  only 
1,294  grams.  The  largest  woman's  brain  recorded  is  1,742 
grams;  she  was  insane  and  died  of  consumption.  The  third 
largest  woman's  brain  recorded  weighed  1,580  grams;  she 
also  was  insane. 

There  is  no  evidence  that  size  of  brain  (or  of  head)  is 
necessarily  connected  with  actual  or  potential  intelligence. 
Usually,  large  individuals  have  large  brains;  men  are  larger 
than  women.  Large  brains  have  no  more  units  than  small 
brains:  the  units  are  large.  A  small  brain  is  no  more  neces- 
sarily handicapped  than  a  small  hand  or  a  small  foot. 

We  do  not  use  the  brains  we  have.  Presumably,  we  no 
more  get  the  maximum  service  out  of  our  brains  than  we 
do  out  of  our  motor-mechanism.    For  every  book  on  how 



to  train  the  brain  there  are  a  dozen  on  how  to  train  the  mus- 
cles. But  not  one  man  in  fifty  who  goes  in  for  muscle-train- 
ing expects  to  put  his  muscles  to  work;  he  sees  physical  cul- 
ture as  physical  beauty. 


We  no  longer  tell  friends  from  enemies  by  smell;  but  we 
often  pick  them  by  the  shape  of  their  nose.  Man's  nose 
is  not  so  striking  as  the  elephant's,  or  even  the  long-nosed 
monkey's,  but  it  features  his  face  and  is  one  of  his  most 
human  and  superfluous  elements.  As  it  is  a  new  acquisition 
— it  began  with  mammals — it  appears  late  in  fetal  life  and 
develops  fully  only  after  birth.  Its  shape  and  size  are  he- 
reditary and  are  distinguishing  traits  of  race.  But  it  has 
no  more  to  do  with  brain  power  than  the  handkerchief  that 
wipes  it. 

As  the  olfactory  nerves  alone  are  connected  with  the  hemi- 
spheres of  the  human  brain,  it  is  inferred  that  the  brain  it- 
self arose  in  connection  with  the  sense  of  smell;  the  original 
brain  was  a  smelling  organ. 

In  mammals  generally,  the  smell  sense  is  the  most  highly 
developed  of  all  senses.  In  monkeys,  it  has  already  begun 
to  diminish.  Some  mammals  have  five  pairs  of  ridges  sup- 
porting the  olfactory  organs;  some  hoofed  animals  have  eight; 
apes  usually  have  three.    Man  has  from  two  to  five  pairs. 

The  nose  in  the  human  embryo  is  at  first  a  pair  of  pits  or 
])ockets  in  the  skin — the  condition  in  fishes.  The  external 
iiose  appears  much  later. 

Man's  reptilian  ancestors  had  a  supplementary  smell 
organ  between  roof  of  mouth  and  floor  of  nose.  With  this 
they  could  sample  odors  while  eating  without  having  to 
sniff.  We — in  common  with  other  mammals — have  its  ves- 
tige in  our  Jacobsons  organ. 

The  ear  also  begins  as  a  pocket,  in  the  first  gill-cleft.  This 
sinks  into  the  head  until  its  outer  opening  is  closed  by  the 



tympanum  or  eardrum.  A  rare  anomaly  is  an  individual  with 
two,  or  even  three,  external  ear  openings ;  these  represent  the 
second  and  third  gill-clefts.  In  some  fishes  the  opening  re- 
mains; their  ear  is  primarily  a  balancing  organ.  Our  equilib- 
rium sense  organ  is  also  located  in  the  inner  ear;  if  our 
semilunar  canals  are  destroyed,  we  cannot  balance  ourselves. 

We  turn  our  head  toward  sounds  or  cup  our  hands  be- 
hind our  ears;  our  ancestors  turned  their  ears.  We  have 
vestiges  of  ear  muscles,  as  do  apes.  Our  external  ears  are 
also  degenerate,  as  are  those  of  the  orang  and  gorilla. 
Some  ears  are  small  and  lie  tight  against  the  head,  as  in  the 
orang;  some  are  large  and  stand  out,  as  do  those  of  the 

At  the  eighth  month  the  rim  or  helix  of  the  fetal  ear 
begins  to  fold  in — an  additional  sign  of  degeneracy.  But 
the  tip  persists  and  generally  may  be  felt,  often  may  be 
seen,  near  the  middle  of  the  infolded  helix.  It  is  called 
Darwin's  point;  Darwin  pointed  out  its  vestigial  character. 

The  lobe,  or  soft  lower  part,  of  the  ear  generally  appears 
at  the  sixth  month  of  fetal  life,  is  found  in  no  animals 
below  apes,  and  in  man  has  no  known  use  other  than  sup- 
port for  ornament.  It  is  said  to  be  larger  in  women  than 
in  men;  it  may  be  absent  in  either  sex. 

Our  eyes  are  compound  and  are  made  up  of  the  same 
three  parts  that  are  found  in  fishes'  eyes.  First,  a  cluster 
of  skin-cells  dig  in  to  form  the  lens;  skin  grows  over  this, 
becomes  transparent,  and  forms  the  cornea.  Next,  a  growth 
from  the  neural  tube  reaches  out  and  ends  in  a  cup  around 
the  lens.  This  cup  becomes  the  retina;  the  stalk  which 
joins  cup  with  tube,  the  optic  nerve.  Cells  from  the  middle 
germ-layer  now  enter  the  cup  and  form  the  transparent 
matter  of  the  eyeball.  The  middle  layer  also  supplies  the 
protecting  coat  of  the  retina.  As  the  lens  is  modified  skin 
structure,  it  is  subject  to  the  horny  change  of  old  age.  Hence 
"cataract"  of  the  eye;  the  lens  has  become  covered  with  a 



The  Asiatic's  eye  is  not  oblique.  The  "slit"  appearance 
is  due  to  the  low  nasal  bridge  supporting  the  upper  lid;  the 
lid  thus  folds  and  appears  "Mongolian."  This  "oblique" 
eye  is  not  uncommon  in  white  children  at  birth;  when  the 
bridge  develops  slowly  it  may  persist  for  months,  even  into 
adult  life. 

In  the  inner  angle  of  our  eye  is  a  little  fold  of  skin  of 
varying  size  called  the  plica  semilunaris.  It  is  a  rudiment 
of  the  third  eyelid  or  nictitating  membrane  that  cleans  the 
eyeballs  of  birds  and  frogs;  their  upper  eyelid  is  immova- 

The  tears  which  wash  our  eyes — otherwise  as  dirty  as  our 
faces — come  from  lachrylnal  glands  in  the  upper  outer 
corner  of  each  eye.  Some  have  additional  tear  glands  at 
the  sides  of  the  eyes,  as  have  reptiles. 

Our  skin  is  a  double  structure.  The  outside,  or  epidermis, 
is  ectoderm;  the  inside,  or  dermis,  is  derived  from  the  meso- 
derm. The  fetal  skin  at  first  is  translucent  and  not  unlike 
that  of  fishes.  During  the  third  month,  the  epidermis  begins 
to  become  horny,  as  it  is  in  adult  life.  It  is  significant  that 
if  we  lose  a  third  of  our  skin — by  fire,  acid,  boiling  liquid, 
or  flaying — we  lose  our  life. 

Color  of  skin  is  an  inherited  trait  and  is  due  to  grains 
of  brown  or  yellow-red  pigment  in  the  dermis.  Entire  ab- 
sence of  pigment  in  skin,  hair,  and  eyes  is  a  developmental 
defect  and  results  in  albinos.  Albinism  is  an  inherited  trait 
and  is  found  in  many  animals.  White  blackbirds  are  as 
common  as  white  black  men.  Pigment  is  probably  due  to 
secretion  of  an  endocrine  gland. 

To  form  a  better  grasping  surface,  the  skin  of  man's, 
monkeys',  and  many  other  mammals'  hands  and  feet  is 
thrown  into  minute  ridges,  especially  prominent  on  the  finger 
tips.  These  ridges  form  loops,  spirals,  and  arches.  In  no 
two  individuals  on  earth  do  they  make  exactly  the  same 
pattern.  Hence  their  unique  importance  as  marks  of  iden- 



At  the  fourth  month,  the  embryo  begins  to  show  a  fine  silky 
hair  coat  or  lanugo  (down).  This  begins  to  be  replaced, 
even  before  birth,  by  a  second  coat  of  different  character. 
The  lanugo  may  persist  as  "down"  on  the  face  of  girls  and 
women,  or  even  all  over  the  body,  as  on  the  so-called  dog- 
faced  people  of  the  menageries.  The  lanugo  probably  rep- 
resents our  adult  ancestral  condition.  But  no  satisfactory 
theory  has  yet  been  advanced  to  account  for  the  fact  that 
man  is  the  least  hairy  of  the  primates. 

Hair  does  not  grow  on  our  bodies  in  haphazard  fashion, 
but  in  lines  and  sets  of  three,  four,  or  five,  each  set  being 
the  hairs  that  grew  beneath  one  scale  of  our  reptilian  ances- 
tors. On  certain  parts,  especially  on  males  in  the  region 
of  the  navel,  may  be  detected  a  vortex  pattern  like  that  at 
the  end  of  the  spine  where  the  tail  once  projected. 

Cats  "feel"  in  the  dark  with  whiskers  or  vibrissas.  Man's 
eyebrows  and  mouth  and  ear  hairs  seem  to  be  the  modified 
descendants  of  such  feelers.  Actual  vibrissas — long,  coarse, 
stiff  hairs — often  appear  in  men,  especially  after  middle  life, 
generally  in  the  eyebrows,  less  often  on  the  end  of  the  nose. 

Man's  hairy  coat  varies  individually  and  in  races.  Because 
of  their  hairy  bodies,  the  aborigines  of  Japan  are  called  the 
Hairy  Ainu.  The  amount  of  hair  on  the  face  and  the  parts 
of  the  body  covered  by  hair  also  vary  in  different  races. 

We  inherit  finger  and  toe  nails,  almost  without  change, 
from  our  animal  ancestors.  The  nails  of  our  big  toe,  thumb, 
and  first  and  second  fingers  tend  to  be  flat — as  they  are  in 
apes;  the  arched  nails  of  our  other  fingers  suggest  the  rounded 
claws  of  certain  mammals  and  are  like  the  long  curved  nails 
of  monkeys. 

Our  skin  is  rich  in  glands.  These  begin  to  develop  during 
the  fifth  month.  The  sweat  glands  reduce  temperature  and 
eliminate  waste.  Sebaceous  or  fat  glands  lubricate  the  skin 
and  hair,  and  in  certain  regions  (armpits,  for  example) 
secrete  an  odor.    Such  odoriferous  glands  are  generally  sex- 



ual  in  character  and  are  highly  developed  in  hoofed  animals. 
In  the  male  musk  deer  of  Central  Asia  the  gland  is  as  big  as 
a  hen's  egg.  Its  secretion  is  the  base  of  certain  man-made 
perfumes.   Consequently,  the  musk  deer  is  almost  extinct. 

Mammals  take  their  name  from  their  mammae — sweat 
glands  peculiarly  modified  to  secrete  milk.  On  the  one-month 
human  embryo  appear  two  mammary  ridges  extending  from 
armpits  to  groin.  A  milk  gland  develops  at  the  upper  end  of 
each  ridge.  The  ridge  then  atrophies  and  disappears.  But 
one  individual  in  every  500  has  supernumerary  glands — 
three,  four,  even  seven  pairs  are  not  unknown.  These  are 
clearly  a  reversion  to  an  earlier  mammalian  condition.  In 
one  case  a  large  gland  developed  in  the  middle  of  the  back. 

At  first  a  depression  appears  in  the  center  of  the  gland — 
and  so  remains  in  the  lowest  order  of  mammals.  From  the 
bottom  of  the  depression  many  little  bases  rise;  these,  in  both 
sexes,  come  to  form  the  nipple  just  before  or  shortly  after 
birth.  The  mammae  develop  no  further  until  puberty,  when, 
in  the  female,  they  are  stimulated  to  further  growth  by  the  sex 
glands.  As  their  function  is  food,  and  as  they  have  been 
known  to  function  in  otherwise  normal  males,  they  are  not 
primary  sexual  characters. 


Now  and  then  a  child  is  born  with  a  common  opening  for 
the  intestine  and  the  urogenital  tract.  This  common  vent  is 
called  a  cloaca  (sewer) ;  it  is  the  normal  condition  in  fishes, 
amphibians,  reptiles,  birds,  and  the  lowest  order  of  mammals. 
In  man  it  represents  a  reversion  to  an  ancestral  type  which 
did  not  disappear  until  marsupials  evolved,  millions  of  years 
ago,  as  the  second  order  of  mammals. 

The  cloacal  condition  is  normal  in  the  human  embryo  dur- 
ing the  second  month;  at  that  time  the  intestine  and  urogenital 
ducts  end  in  a  common  chamber.   Not  until  the  tenth  week  is 



it  possible  to  distinguish  a  male  from  a  female  fetus.  Until 
this  time  the  external  and  internal  anatomy  is  identical  for 
both  sexes. 

With  the  eighth  week  the  cloacal  condition  ceases  and  the 
embryo  develops  into  a  male  or  a  female.  Whether  it  is  to 
become  male  or  female  is  probably  determined  when  the 
ovum  is  fertilized.  The  decisive  factor  is  not  known,  nor  is 
it  likely  that  we  shall  discover  means  by  which  the  ovum  will 
develop  into  male  or  female  according  to  our  desire  for  son 
or  daughter.  As  we  shall  see  later,  the  sex  glands  themselves 
presumably  secrete  a  hormone  which,  carried  by  the  blood, 
causes  the  marvelous  changes  whereby  the  neutral  rudimen- 
tary organs  develop  in  one  or  the  other  direction. 

The  anatomical  structure  on  which  these  hormones  may  act 
consists  of  four  parallel  tubes  at  the  hind  end  of  the  body, 
opening  into  the  cloaca.  The  outer  tubes,  or  Wolffian  ducts, 
will  carry  the  male  glands;  the  inner  pair,  or  Muellerian 
ducts,  will  become  the  oviducts,  or  Fallopian  tubes. 

If  the  embryo  is  to  become  a  male  the  inner  tubes  atrophy; 
the  Wolffian  ducts  become  the  vas  deferens;  the  cloaca  open- 
ing closes  to  form  the  scrotum.  If  female,  the  cloaca  remains 
open;  the  oviducts  grow  together  in  the  lower  part  to  become 
the  uterus,  the  upper  becoming  the  Fallopian  tubes;  the  Wolff- 
ian ducts  persist  as  vestiges  in  the  broad  ligament.  In  the 
male  the  sex  glands  descend ;  in  the  female  they  remain  within 
the  pelvic  cavity.  The  migration  of  the  glands  in  the  male 
is  common  to  most  mammals,  but  only  in  man,  due  to  his 
upright  gait,  do  the  inguinal  canals  through  which  they  pass 
remain  weak  spots  which  may  permit  the  escape  of  a  loop  of 
the  intestine,  causing  hernia. 

The  significant  fact  is  that  the  human  embryo  of  eight 
weeks  has  the  makings  of  a  male  or  a  female.  It  follows  that 
neither  sex  possesses  any  anatomical  parts  which  are  not 
found  in  homologous  parts  in  the  other  sex.  The  beginnings 
of  all  the  parts  are  present  from  the  start;  later  they  come  to 



differ.  By  change,  by  shift  in  position,  and  by  growth  or 
atrophy,  the  original  neutral  mechanism  becomes  male  or 

Most  plants  and  many  lower  animals  are  hermaphrodites 
(Hermes- Aphrodite) :  the  organs  of  both  sexes  are  combined 
in  one  individual.  Higher  in  the  scale  of  animal  life  true 
hermaphrodites  disappear.  But  sometimes  in  an  otherwise 
normal  human  embryo  certain  parts  fail  to  complete  their 
normal  development.  The  result  is  an  individual  anatom- 
ically neither  a  fully  formed  male  nor  a  female;  such  are 
called  hermaphrodites.  But  no  human  being  functions  both 
as  male  and  as  female. 

While  the  sex  glands  or  gonads  appear  at  the  sixth  week, 
they  show  no  structural  difference  as  to  their  future  sex;  yet 
the  cells  within  under  the  microscope  are  already  definitely 
of  one  or  the  other  sex.  If  female,  the  cells  are  of  the  ovum 
type,  large  and  rounded;  if  male,  the  cells  are  of  the  sper- 
mium  type,  very  small,  very  long,  and  ending  in  a  fine  process, 
or  tail. 

The  function  of  the  renal  organs  or  kidneys  is  to  preserve  a 
certain  constancy  in  the  blood  stream  and  to  eliminate  certain 
noxious  elements  from  the  body.  To  perform  this  double 
function,  three  types  of  kidneys  have  been  evolved.  The  de- 
veloping human  embryo,  as  well  as  embryos  of  other  mam- 
mals, rehearses  this  story,  all  three  types  appearing  in  pre- 
natal life. 

The  first  renal  organ  to  appear,  the  head  kidney,  becomes 
an  appendage  of  the  sex  glands.  The  second,  or  Wolffian 
body,  becomes  part  of  the  seminiferous  duct  in  the  male;  in 
the  female  it  remains  as  the  parovarium,  a  vestige  in  the 
broad  ligament  between  uterus  and  pelvic  wall — it  is  often 
prone  to  disease.  Finally,  true  kidneys  develop.  These  are 
at  first  furrowed,  as  they  remain  in  some  mammals;  later  they 
become  smooth.  Sometimes  the  furrows  persist,  reminders  of 
earlier  days. 




The  alimentary  canal  appears  first  as  a  closed  tube  within 
the  body.  It  opens  later  at  each  end,  the  upper  opening  be- 
coming part  of  the  mouth  cavity.  Below  this  opening  four 
crevices  appear  which  represent  the  internal  arrangement  of 
the  fish-like  gill-clefts.  Below  these  crevices  a  single  sac-like 
structure  appears;  this  divides,  and  by  further  subdivisions 
becomes  the  right  and  left  lung.  From  the  region  of  the 
crevices  outgrowths  of  the  alimentary  canal  develop  into  thy- 
roid, epithyroid,  and  thymus  glands.  From  the  extreme  upper 
end  of  the  embryonic  canal  develops  a  portion  of  another  im- 
portant gland,  the  pituitary.  The  stomach  at  first  is  merely 
an  enlargement  of  the  canal.  Just  below  the  stomach  two 
outgrowths  of  the  canal  develop  into  the  important  glands  of 
digestion,  pancreas  and  liver. 

Without  further  details  of  fetal  development  it  will  be 
worth  while  to  recall  certain  variations  in  the  systems  of 
digestion,  respiration,  and  circulation,  which  are  significant 
in  light  of  our  animal  ancestors. 

Our  dentition  is  as  well  adapted  for  spinach  as  for  beef- 
steak, specialized  for  neither.  Our  front,  or  incisor,  teeth 
are  only  fair  cutters;  our  bicuspids,  or  premolars,  are  not 
strong  enough  to  crunch  bones;  our  grinders,  or  molars,  are 
not  very  good  millstones.  Our  snarling  muscle  discloses  no  ^ 
such  canines  as  the  flesh-eaters  stab  and  tear  their  prey  with. 
Our  teeth  are  on  the  go.  A  perfect  "civilized"  set  is  rare. 
In  hundreds  of  skulls  I  collected  in  New  Guinea  there  was  not 
one  imperfect  set — all  strong,  sound,  beautifully  aligned. 

Man,  apes,  and  Old  World  monkeys  have  thirty-two  teeth, 
eight  on  each  side  of  each  jaw:  two  incisors,  one  canine,  two 
bicuspids,  three  molars.  Man's  mammalian  ancestor  had 
forty-four  teeth:  three  incisors,  one  canine,  three  bicuspids, 
four  molars. 

Variation  rules.  Often  there  is  only  one  incisor,  an  in- 
herited condition;  there  may  be  three  incisors.    The  canine 



is  rarely  absent,  but  it  may  be  a  tiny  stump;  more  often  it 
is  over-developed,  disfiguring  the  face.  A  third  bicuspid  is 
not  rare.  A  fourth  molar  is  more  rare,  but  frequent  enough 
to  be  suggestive.  The  third  molar,  or  wisdom  tooth,  is  a  bad 
lot  among  whites — jaws  too  short;  it  comes  in  at  any  angle, 
varies  in  its  cusps,  often  is  a  mere  stump,  often  never  erupts 
at  all. 

Most  fishes  have  teeth  in  the  roof  of  the  mouth  as  well  as 
in  the  jaws  proper.  They  do  not  occur  in  "sets,"  but  are  end- 
lessly shed  and  reproduced.  In  the  fish  embryo  the  dental 
germs  appear  before  the  jawbones;  in  the  human  embryo  also. 
In  the  infant's  mouth  is  a  ridge  with  from  five  to  seven  pairs 
of  cross  ridges;  they  are  even  more  pronounced  in  the  fetus. 
They  disappear  with  age.  Apes  have  ten  pairs  of  these 
ridges.  In  pigs,  they  are  strong  enough  to  crush  food.  Their 
presence  in  man,  with  an  occasional  more  or  less  complete 
third  set  of  teeth,  points  to  fish  and  reptile  days:  teeth  in  the 
roof  of  the  mouth,  endlessly  replaced. 

Tonsils  appear  in  fetal  life  as  pockets.  They  shift  position 
and  develop  into  prominent  bodies.  With  adult  life  they  be- 
gin to  disappear,  leaving  pockets  prone  to  disease.  They 
are  not  understood  and  are  never  alike. 

The  cricket's  chirp  was  the  first  music  on  earth,  but  it  was 
instrumental.  The  first  voice  was  the  amphibian's.  Frog, 
bird,  cat,  dog,  and  man  would  be  silent  without  a  larynx; 
without  the  human  larynx  there  could  have  been  no  human 
speech  or  Tower  of  Babel.  Ours  is  a  wonderful  larynx;  let 
us  get  such  joy  as  we  can  from  it.  Our  developing  respira- 
tory system  suggests  fish;  in  our  youth  it  is  a  hotbed  of  infec- 
tion. Our  vocal  cords  are  human  only  in  their  high  develop- 
ment. But  we  all  have  the  blind  pocket  between  true  and 
false  cords  which  served  as  a  resonator  and  so  strengthened 
the  roar  by  which  our  ancestors  frightened  their  foes  and 
called  their  mates.  In  man  it  varies,  but  is  never  so  deep  as 
in  the  gorilla. 

The  vermiform  appendix  is  the  worm  its  name  implies.  It 



is  a  feeble,  narrow,  tapering  blind  alley,  opening  by  a  small 
moiitli  into  the  large  intestine.  At  birth,  in  size  and  form  it 
is  like  an  ape's.  At  puberty  it  begins  to  shorten;  it  is  about 
closed  in  every  fourth  adult;  in  every  thirtieth  adult  it  is 
closed  throughout.  It  shrivels  up  with  old  age.  It  may  be  ten 
times  longer  in  one  brother  than  in  another.  It  is  a  true 
vestige.  It  is  predisposed  to  disease;  appendicitis  is  a  fash- 
ionable operation.  Only  apes  in  captivity  develop  append- 
icitis. For  an  appendix  that  functions  we  must  go  to  the 
lowest  monkeys. 

The  liver  usually  has  two  lobes — it  may  have  none,  it  may 
have  twelve;  it  may  have  two  gall-bladders — it  may  have 

The  abdominal  viscera  in  the  human  embryo  are  not  human 
in  their  arrangement.  Only  later  does  the  mesentery,  or  sheet 
of  membrane  connecting  the  bowel,  become  attached  to  the 
back  wall  of  the  abdomen  and  so  hold  it  in  place  and  in  per- 
pendicular position.  Sometimes  the  mesentery  is  found  ar- 
ranged as  in  monkeys.  The  loosely  attached  bowel  easily 
twists  and  becomes  obstructed. 

There  are  more  than  mere  structural  variations  in  our  food 
canal;  there  are  signs  of  degeneracy — in  teeth,  in  jaws  and 
throat,  and  in  the  large  intestine.  Changed  diet  does  it.  To 
digest  raw  food  our  ancestors  had  to  chew  it.  They  had  strong 
jaws,  heavy  muscles,  sound  teeth  properly  aligned,  big  throats, 
and  a  colon  that  could  digest  husks  of  grain  and  skins  of 
fruits  and  vegetables. 

The  lobes  of  the  lungs  vary  in  number  and  position.  Due 
to  man's  upright  gait,  the  heart  has  come  to  rest  on  the  dia- 
phragm. In  monkeys  the  azygos  lobe  of  the  lung  lies  be- 
tween. In  man  there  is  always  a  remnant,  of  varying  size,  of 
this  lobe. 

The  chief  business  of  the  fish  heart  is  to  pump  blood  to  the 
gills;  of  ours,  to  the  body.  The  human  embryo  at  the  bran- 
chial-cleft stage  has  a  tubular  heart  of  four  chambers.  When 
lungs  begin  to  develop  the  first  chamber  becomes  part  of  the 



auricle,  the  fourth  chamber  part  of  the  ventricle.  These  then 
divide  into  right  and  left;  the  right  passes  venous  blood  to  the 
placenta,  the  left  receives  this  blood  and  sends  it  to  the  body. 
The  fourth  chamber  may  fail  to  develop  normally;  the  blood 
passes  imperfectly  into  the  pulmonary  artery  and  so  is  not 
properly  oxidized.  Sometimes  a  heart  is  found  with  the  ves- 
tige of  a  valve  which  functions  in  animals  no  higher  than 
frogs  and  salamanders.  Variations  in  the  blood  vessels  are 
endless.  Even  the  great  artery  leading  from  the  heart  is  sub- 
ject to  astonishing  variations — all  harking  back  to  great 
changes  in  the  circulatory  system  since  man  evolved  from  a 
water-breathing  animal. 

When  we  recall  the  branchial-clefts  in  the  neckbend  of  the 
human  fetus — and  their  fate;  also  that  for  ages  man's  an- 
cestors derived  their  oxygen  from  water  through  gills  and  not 
from  air  through  lungs;  also  that  man  only  recently  left  the 
trees — ^we  must  expect  to  find  great  variation  in  human  mouths 
and  throats,  in  the  food  and  air  canals  below,  and  in  the 
marvelously  intricate  system  which  delivers  blood  to  every 
cell  in  the  complex  body. 


Suppose  it's  twins!  One  in  every  hundred  births  is.  Ire- 
land averages  higher — one  pair  for  every  seventy-two  births. 

Twins  run  in  families.  A  mother  who  has  twins  is  likely 
to  bear  more  twins.  She  is  called  a  "repeater."  She  prob- 
ably inherits  twin  capacity — and  transmits  it.  Her  anatomy 
is  such  that  twins  are  possible.  That  she  bears  twins  only  one- 
fifth  of  the  time  is  probably  due  to  her  own  internal  weak- 
ness. Twins  occur  also  in  other  mammals  that  ordinarily 
bear  but  one  individual  at  a  time.  Triplets  occur  once  in 
every  7,000  births;  quadruplets,  only  once  in  every  370,000 

There  are  two  kinds  of  twins:  twins;  identical  twins.  The 
first  type  develops  independently  from  two  ova  that  happen 



to  mature  at  the  same  time.  Each  ovum  develops  its  own 
chorion  and  placenta — though  the  two  placentas  may  partially 
fuse.  They  are  not  true  or  "identical"  twins,  merely  acci- 
dents as  to  time  of  birth.  Both  may  be  boys  or  girls,  or 
they  may  be  brother  and  sister.  They  vary  as  brothers  and 
sisters  of  a  family  normally  vary. 

Identical  twins  are  always  of  the  same  sex:  either  both 
boys  or  both  girls.  They  develop  from  a  single  ovum,  in  the 
same  chorion,  and  receive  food  and  oxygen  through  the  same 
placenta,  to  which  each  is  attached  by  its  own  umbilicus. 

There  need  be  no  doubt  as  to  whether  twins  are  just  twins 
or  identical:  if  identical,  they  are  always  of  the  same  sex 
and  there  is  only  one  placenta ;  if  there  are  two  placentas,  or 
if  they  are  of  different  sex,  they  cannot  be  true  twins. 

Sometimes  identical  twins  are  so  alike  that  only  a  string 
around  the  thumb,  or  some  such  device,  will  enable  the  mother 
to  distinguish  one  from  the  other. 

It  was  formerly  held  that  identical  twins,  triplets,  quad- 
ruplets, etc.,  resulted  from  multiple  fertilization  of  one  ovum. 
But  twins  and  monsters  can  be  produced  artifically  in  biologic 
laboratories.  Fish  monsters  can  be  grown  from  eggs  deprived 
of  enough  oxygen.  Monsters  of  all  sorts  have  been  grown  by 
separating  the  young  embryo  into  two  or  more  parts.  Perfect 
twins  have  been  grown  from  the  two  cells  of  the  dividing 
ovum  shaken  apart. 

Human  twins,  triplets,  etc.,  presumably  arise  from  early 
separation  of  the  ceils  into  which  the  original  ovum  divided. 
If  the  division  is  not  complete,  the  result  is  twin,  triplet,  or 
even  quadruplet  monsters.  These  may  take  any  conceivable 
form,  from  twins  bound  together  only  at  one  spot,  to  a  twin 
inside  the  body  of  the  other.  An  autopsy  recently  revealed 
a  tiny  parasitic  twin  in  an  abdominal  tumor,  carried  within 
its  twin  brother's  body  for  half  a  century.  He  had  never 
known  of  its  existence. 

Double  monsters  may  have  one  head,  two  bodies;  two 
heads,  one  body;  one  head,  two  necks,  one  chest,  two  bodies 



below  the  diaphragm.  One  twin  may  be  fully  developed; 
attached  to  its  body  is  an  arm  or  a  leg  of  the  other.  One  twin 
may  develop  no  heart,  receiving  its  blood  through  its  umbili- 
cus; it  perishes  at  birth. 

In  "Siamese"  twins,  the  embryo  divides  into  two  at  both 
ends  but  not  in  the  middle;  if  they  share  vital  organs,  they 
cannot  be  separated  by  the  knife.  The  Two-headed  Nightin- 
gale, Millie  and  Christina,  had  two  heads,  one  body,  four 
legs;  she  (or  they)  could  sing  by  each  head  and  each  head 
could  control  two  or  four  legs.  The  famous  Scottish  Brothers 
— clever  musicians  and  linguists — were  one  individual  below 
the  waist,  above  quite  distinct  except  at  the  back. 

Single  monsters  may  have  no  arms  or  legs ;  no  abdominal 
wall ;  a  brain  outside  the  skull  or  other  malformation  of  brain, 
skull,  or  face;  a  Janus  face;  a  Cyclopean  eye.  There  is  no 
end  to  the  range  of  malformation. 

Other  abnormalities  are  only  to  be  understood  in  the  light 
of  man's  ancestry.  Part  or  parts  stop  growth  before  normal 
human  condition  is  reached.  They  point  the  road  man  trav- 
eled. Some  are  not  easy  to  classify:  vestiges  of  ancient  days, 
part  of  our  normal  heritage;  faulty  cell  division,  unfavorable 
environment,  faulty  implantation,  or  defective  germ-plasm? 
In  one  unique  case  the  ovum  had  become  implanted  clear  out- 
side the  abdominal  cavity,  just  under  the  skin  over  the  ab- 
domen. It  had  begun  to  develop  and  was  diagnosed  as  a 

The  lower  jaw  may  be  deformed;  no  sharp  line  between 
face  and  neck,  ears  almost  meeting  in  front.  Reversion  to 
a  fish  condition?  No  doubt  as  to  what  happened — the  first 
gill-arch  of  the  embryo  failed  to  develop.  It  hardly  de- 
velops at  all  in  lowest  fishes. 

There  may  be  an  extra  finger  or  toe,  always  outside 
thumb  or  little  finger.  Is  this  an  ancestral  echo,  or  did  a 
finger-bud  divide?  The  tenth-of-an-inch-long  four-weeks-old 
fetus'  limbs  begin  as  tiny  buds  and  soon  look  like  paddles. 
Before  the  buds  appear,  the  fetus  is  limbless.  Sometimes 



the  paddles  never  develop  into  arms  or  legs;  they  remain 
mere  flaps.  Or,  the  fingers  and  toes  may  remain  hidden 
in  the  flaps.  Or,  some  or  all  of  the  fingers  or  toes  may  be 
webbed — as  they  are  in  the  embryo. 

Rabbits  are  not  "hare-lipped";  their  upper  lip  is  cleft  in 
the  middle.  Our  lip  begins  as  three  pieces;  if  they  fail  to 
join,  the  cleft  is  between  one  or  both  nostrils  and  the  mouth 
— never  in  the  middle  of  the  lip.  A  double  "hare-lipped" 
man  is  shark-lipped. 

We  can  eat  and  breathe  at  the  same  time  because  our 
mouth  is  shut  off"  from  our  nose  by  the  palate  or,  roof  of 
our  mouth.  Our  palate  begins  as  two  bones;  they  join  in 
the  ninth  week  of  fetal  life.  Sometimes  they  do  not;  result: 
cleft  palate,  as  have  frogs,  snakes,  and  birds. 

Cysts  or  hollow  tumors  may  be  found  in  any  part  of  the 
body.  When  lined  with  skin,  they  are  called  dermoid.  They 
are  thought  to  arise  from  germ-cells  which  strayed  away 
from  the  sex-glands. 

Generally,  abnormal  development  is  due  to  disease  in 
the  uterus  or  to  such  faulty  attachment  of  embryo  that  its 
nourishment  is  impaired.  But  ova  may  develop  normally  in 
abnormal  positions,  even  outside  the  uterus.  Mothers  can- 
not influence  their  intrauterine  growth  by  "scares,"  etc. 
Possibly  her  blood  altered  by  fever  might  upset  normal  de- 
velopment. It  is  known  that  tetanus,  diphtheria,  and  typhoid 
toxins  and  antitoxins  can  pass  from  the  host  into  fetal  cir- 
culation. It  also  seems  that  the  germs  of  typhoid,  and 
possibly  tuberculosis,  may  similarly  pass  from  host  to  fetus. 
But  it  must  be  understood  that  there  is  no  interchange  of 
blood  between  the  two,  nor  any  commingling  of  body  fluids 
or  nerve  tissue.    The  fetus  is  a  true  parasite. 


In  upright  gait,  balanced  skull,  and  arms  free  at  the  sides 
of  the  body,  we  diff"er  most  from  the  only  animals  that  ape 



us.  This  upright  gait  is  maintained  by  action  of  muscle 
on  bone.  We  hang  on  a  bony  skeleton,  largely  levers.  We 
move  by  setting  those  levers  in  motion.  To  put  us  across 
a  hundred  yards  in  ten  seconds,  the  skeleton  must  be  mature. 
If  our  bones  were  cartilage  we  would  be  wonderful  con- 
tortionists, but  our  upright  gait  would  collapse. 

Our  ancestors  went  on  all-fours.  In  acquiring  the  up- 
right gait,  the  axis  of  the  body  changed  from  horizontal  to 
perpendicular.  This  necessitated  changes  in  every  bone  and 
muscle  in  the  body  and  a  complete  overhauling  of  every- 
thing inside — lungs,  circulation,  abdominal  viscera^ — every- 

Our  pelvic  girdle  is  a  broad,  shallow  basin;  it  supports 
viscera.  The  keystone  of  the  girdle  is  the  sacrum.  It  sup- 
ports the  backbone  and  locks  the  arch  behind.  The  dog's 
sacrum  is  long  and  narrow;  ours,  broader  than  it  is  long. 
The  sacrum  at  birth  varies  from  four  to  seven  vertebrae. 
These  unite  into  one  bone;  but  the  first,  and  sometimes  the 
second,  never  unites  with  the  others. 

Above  the  sacrum  is  the  vertebral  column  proper:  seven 
neck  or  cervical,  twelve  thoracic,  and  five  lumbar  vertebrae 
— -twenty-four  in  all.  But  there  may  be  six  or  eight  cervical; 
eleven  or  thirteen  thoracic;  four  to  six  lumbar.  At  birth, 
most  of  us  have  twelve  pairs  of  ribs ;  some,  only  eleven ;  some, 

Seven  pairs  of  ribs  join  our  sternum,  or  breastbone;  there 
may  be  only  six,  there  may  be  eight.  The  first  pair  are 
sometimes  mere  rudiments.  Our  floating  ribs  are  not  so 
important  as  when  we  walked  on  all  fours;  they  vary  in 
number  and  size.  The  sternum  is  less  important  than  for- 
merly; it  varies  enormously.  Two  little  bones  sometimes 
found  on  its  upper  border  are  vestiges  of  tlie  episternal 
bones  of  the  lowest  mammals. 

No  man-made  column  is  so  delicately  adjusted,  so  slender, 
or  so  well  balanced  as  our  spine.  Its  sigmoid,  or  "S"  curve, 
gives  elasticity  to  our  body,  grace  to  our  carriage,  fine  lines 



to  our  back,  and  saves  our  brain  from  jar  and  shock.  The 
really  human  curves  develop  after  birth,  especially  the  lum- 
bar curve  in  the  "small"  of  our  back.  The  infant  cannot 
stand  straight  up  because  it  has  not  yet  acquired  a  stand- 
up-straight  backbone. 

Our  backbone  ends  in  small  rounded  bones  about  the 
size  of  peas.  They  are  the  coccyx,  skeleton  of  our  tail. 
They  may  grow  fast  to  the  sacrum,  and  by  restricting  the 
size  of  the  pelvic  opening  give  trouble  in  childbirth.  The 
orang  has  only  three  tail  bones;  we  generally  have  five. 
Like  the  apes,  we  also  have  vestiges  of  muscles  which  once 
moved  the  tail,  blood  vessels  which  nourished  it,  nerves 
which  connected  it  with  the  brain. 

There  is  no  tailed  race  in  Africa — as  the  ancients  be- 
lieved. Man  withdrew  his  tail  beneath  his  skin  before  he 
was  really  man,  but  nature  now  and  then  forgets  to  with- 
draw the  fetal  tail.  One  adult  tail  measured  ten  inches. 
Such  tails  are  usually  "soft" — no  tail  bones  outside  the 
body.  But  a  two-inch-long  tail  with  bones,  nerves,  blood 
vessels,  muscles,  and  hair,  is  known.  Tail  or  no  tail,  the 
hair  keeps  on  growing  in  a  whorl  as  though  the  tail  were* 

The  upper-arm  bone  assumes  its  human  form  only  after 
birth,  when  it  also  begins  to  twist,  as  does  the  femur,  to  con- 
form to  its  new  position  at  the  side  of  the  body.  Above  its 
lower  articulating  surface  is  a  thin  and  shallow  plate,  often 
perforated — as  in  certain  monkeys.  Sometimes  there  is  a 
hole  or  foramen  at  the  side;  it  protects  a  nerve — as  it  did  in 
our  reptilian  ancestors  ten  million  years  ago. 

Human  history  may  not  start  with  man's  foot,  but  our 
foot  is  as  human  as  our  hands.  Its  bones  show  coming  and 
going  changes.  The  big  toe  is  the  strongest  and  is  more 
powerful  in  man  than  in  any  ape:  it  is  coming.  But  most 
of  it  comes  after  birth;  baby's  big  toe  is  a  poor  affair.  The 
little  toe  is  going.  In  one  individual  out  of  every  three  it 
has  lost  a  joint.    But  not  on  account  of  tight  shoes — they 



can  make  corns,  but  cannot  change  heredity;  the  third  bone 
of  the  little  toe  is  as  often  absent  in  feet  which  were  never 

Our  skull  is  no  more  human  than  are  the  bones  of  our 
foot  or  of  our  pelvis.  It  is  shorter  in  front,  longer  at  the 
back,  better  balanced  on  the  spine:  adaptations  to  an  up- 
right gait  and  a  larger  brain. 

Man  has  a  flat  face  and  a  sizable  chin  when  he  has  short 
jaws.  But  jaws  vary,  and  long  or  prognathic  jaws  change 
the  countenance.  The  roof  of  our  mouth  was  once  longer 
than  broad — U-shaped,  as  in  some  men  and  all  apes.  With 
civilized  food,  the  jaws  are  shortening;  the  hard  palate 
tends  to  become  elliptical  in  shape. 

In  fetal  life  we  have  a  pair  of  intermaxillaries  between 
the  upper  jaw  bones.  At  birth  the  suture,  as  skull  joints 
are  called,  between  them  can  barely  be  seen;  by  maturity,  not 
at  all.  The  suture  often  persists,  obviously  atavistic.  The 
chin,  or  mental  point  of  the  lower  jaw,  has  nothing  to  do 
with  "mentality."  It  is  a  human  trait,  but  not  of  all  men 
equally.  Some  have  "strong"  chins,  some  next  to  no  chin 
at  all. 

We  have  two  nasal  bones.  But  in  some  men  and  all 
monkeys  they  become  one;  no  real  bridge  then  to  the  nose. 
Sometimes  the  bones  are  small  and  flat:  no  bridge  at  all. 

The  brain  can  grow  only  as  long  as  the  three  big  sutures  of 
the  skull  remain  open.  They  begin  to  close  at  the  age  of 
forty:  the  one  at  the  back  first;  the  fore  part  of  the  brain 
can  keep  on  growing.  In  animals  the  sutures  close  earlier 
than  in  man,  the  front  ones  first.  They  may  close  early  in 
man;  they  may  persist  till  old  age. 

WThen  one  or  another  skull  suture  closes  prematurely, 
curiously  shaped  heads  result.  The  "boat-shaped"  head  is 
due  to  premature  closing  of  the  parietal  suture.  When  all 
the  sutures  close  prematurely,  the  skull  becomes  solid  as 
though  a  single  bone.  The  brain  can  grow  no  more.  Idiocy 
results — the  "Aztec"  people  of  the  circus. 



The  frontal  bone  begins  as  two;  shortly  after  birth  they 
have  become  one,  the  suture  disappears.  But  the  suture 
may  persist  throughout  life. 

Most  of  us  have  about  310  muscles  on  each  side  of  our 
body.  They  are  subject  to  such  variation  that  Testut,  a 
noted  French  anatomist,  required  900  pages  to  describe 
them.  Some  of  us  may  have  3  muscles  an  ape  would  be 
ashamed  to  own,  hangovers  from  such  a  remote  past. 

We  marvel  at  the  agility  of  monkeys  and  are  astonished 
at  the  human  quality  of  their  actions.  Do  we  not  often 
expect  them  to  smile?  The  smile  never  comes:  they  have 
no  muscle  to  smile  with.  Even  the  chimpanzee  cannot  ex- 
press with  its  face  the  emotions  we  think  it  should;  its 
facial  muscles  are  less  perfectly  developed,  less  sharply 
defined,  than  ours.  In  monkeys,  they  are  even  less  differ- 

One- fourth  of  all  our  muscles  are  in  our  neck  and  face! 
The  human  face  can  light  up  or  cloud  over  because  its 
muscles  are  attuned  for  complex  action — keyed  to  the  human 

Facial  muscles  in  mammals  below  man  are  more  simple. 
We  look  for  intelligence  in  the  eyes  of  a  horse,  not  in  the 
expression  of  its  face.  When  it  needs  to  flick  a  fly  from  its 
face  or  shoulder,  it  moves  a  muscle  buried  in  the  skin. 
Such  a  muscle  covers  many  animals  like  a  blanket. 

We  all  have  bits  of  this  skin  muscle — some  of  us  more, 
some  less,  even  on  the  chest  and  back.  Usually  we  cannot 
twitch  it;  we  send  a  hand  after  the  fly.  We  have  traces  of 
it  in  our  scalp;  a  few  have  enough  to  move  the  whole  scalp. 
Most  of  us  can  wrinkle  our  forehead — and  do,  when  per- 
plexed. Apes  use  this  muscle  both  in  pleasure  and  to  frighten 
enemies.  We  all  have  vestiges  of  the  muscles  dogs  use  to 
pull,  push,  and  lift  their  ears;  some  can  even  wriggle  them. 

So,  while  the  skin  muscle  of  our  face  and  shoulders  tends 
to  disappear,  the  deeper  facial  muscles  show  progressive 
variation.  They  are  among  our  most  recent  acquisitions.  We 



retain  the  muscle  by  which  the  dog  shows  its  canine  tooth :  w^e 
can  all  snarl.  But  the  muscle  by  which  we  smile  is  not  so 
regularly  present;  the  man  of  gloom  may  have  no  risorius. 

Variations  in  muscles  about  the  nose  and  mouth,  necessary 
for  speech,  are  usually  forward-looking;  they  give  the 
"speaking  likeness"  to  man.  Often  they  reveal  what  the 
mind  is  trying  to  hide.  Only  as  we  grow  in  experience  can 
we  make  our  face  a  mask  to  belie  our  emotions.  This  is 
because  the  face  is  primarily  under  the  control  of  the  auto- 
nomic nerves;  they  act  of  their  own  sweet  will  and  are  by 
nature  honest.  But  by  and  by  our  brain  learns  to  get  con- 
trol of  them;  we  force  our  face  to  wear  a  smile  when  our 
heart  would  bid  our  eyes  to  weep. 

The  long  flat  rectus  muscles  which  extend  upward  from 
our  pubes  once  helped  to  support  our  abdomen.  In  our 
upright  gait  they  are  of  no  great  use.  Usually  they  end  in 
the  fifth,  sixth,  and  seventh  ribs;  they  may  end  in  the  fifth; 
they  may  extend  up  to  the  second,  as  they  do  in  the  lowest 

The  small  pyramidalis  resting  on  the  rectus  abdominis 
muscle  may  be  absent  on  one  or  on  both  sides ;  it  may  extend 
a  third  of  the  way  up  to  the  navel,  or  all  the  way.  The 
kangaroo  needs  it  to  support  the  pouch  in  which  she  carries 
her  young.  Man  has  carried  his  young  in  his  arms  for  ages, 
but  the  pyramidalis  hangs  on  like  a  bad  habit.  The  little 
sternalis  muscle  of  the  breast  knows  it  has  outworn  its  use- 
fulness; it  is  found  in  one  of  every  twenty- five  individuals. 

We  flex  our  fingers  by  delicate  muscles  beautifully  special- 
ized. The  long  clumsy  flexor  of  our  palm  was  good  enough 
for  our  ancestors;  it  is  not  good  enough  for  us.  It  is  absent 
in  one  man  out  of  every  ten. 

Our  arms  are  free;  they  have  not  forgotten  that  they  were 
once  legs.  Of  36  bodies  examined,  292  variations  were 
found  in  the  arm  muscles,  119  in  the  leg.  Our  immediate 
ancestors  were  four-handed,  we  are  two-footed.  But  when 
baby  gets  on  the  floor,  it  pulls  with  its  fore  and  pushes  with 



its  hind  limbs:  just  as  we  once  crawled  up  out  of  water  on 
to  dry  land. 

Palmists  rarely  read  the  pad  at  the  outer  edge  of  our 
palm — or  know  that  we  have  one  like  it  on  the  sole  of  our 
foot;  both  protect  deep-lying  muscles  from  injury  in  walk- 
ing. The  palm  pad  has  its  own  palmar  muscle  in  one  man 
out  of  every  ten.  It  helped  to  work  the  pads  which  pro- 
tected the  muscles  and  tendons  beneath.  To-day,  it  is  as 
atavistic  as  the  pad  itself;  we  gave  up  walking  on  our  hands 
about  2,000,000  years  ago.  As  for  "lines"  of  fate  and 
marriage,  and  the  "girdle  of  Venus,"  they  can  all  be  "read" 
in  the  hands  and  feet  of  monkeys,  and  to  a  certain  extent  in 
a  baby's  foot — or  in  the  fetal  hands  and  feet.  Palmistry  is 
as  dead  as  phrenology.  Anyone  who  can  read  "character" 
or  "mental  capacity"  from  head  bumps  or  palm  lines  is  a  J 
wizard  and  should  be  paid  accordingly. 

What  does  it  all  mean,  this  astounding  range  of  varia- 
tion, on  which  I  have  barely  touched?  There  they  are,  by  the 
thousands,  by  unnumbered  thousands.  Shall  we  say  that 
they  lie,  that  our  levator  coccygis  never  lifted  a  tail,  that  our 
curvator  coccygis  never  curved  one,  and  that  our  attollens 
auriculam  never  lifted  an  ear?  Or  shall  we  say  that  we 
are  walking  museums  of  comparative  anatomy  and  try  to 
find  out  whence  we  came  and  whither  we  are  going?  This  is 
certain:  there  is  no  fixed,  standardized,  perfect,  or  biolog- 
ically ideal  human  body;  there  are  no  two  human  bodies  quite 
alike.  Each  one  of  us  reeks  with  evidence  that  our  ancestors 
were  not  the  two-handed,  two-footed  creatures  we  are  now; 
that  they  had  no  talking  muscles;  that  they  could  not  back 
up  their  talk  with  a  speaking  countenance;  and  that  they 
could  not  balance  their  heads  on  their  spines. 

Some  variations  are  atavistic  or  vestigial.  Like  the  buttons 
on  our  coat  cuff's,  they  no  longer  function;  like  parlor 
boarders,  they  often  make  trouble.  They  are  hangovers 
from  a  remote  past.  They  are  prone  to  disease;  we  should 
be  better  off"  without  them.    Some  are  retrogressive,  weak 



sisters  of  our  body,  functioning  in  a  half-hearted  way;  we 
could  do  without  them — many  of  us  do.  Some  are  progres- 
sive, a  little  bit  more  than  human;  they  point  to  further 
change  in  man's  physical  structure. 

Taken  together,  they  bridge  every  gap  and  make  a  com- 
plete story.  They  prove  that,  while  our  eyes  look  forward, 
our  body  has  not  forgotten  its  humble  origin — and  carries 
some  dead  wood  we  were  well  rid  of,  such  as  appendix,  tail, 
snarling  muscle.  Our  proneness  to  hernia  and  prolapse  of 
the  uterus  is  only  one  of  the  many  proofs  that  our  body  is 
not  yet  perfectly  adapted  to  an  upright  gait. 


On  the  day  we  are  born  we  have  used  up  only  2  per  cent 
of  our  allotted  growth  power.  We  can  grow  98  per  cent  more 
if  we  are  spared. 

We  double  our  weight  the  first  six  months;  a  calf  does  it 
in  fifty  days;  a  dog,  in  eight.  We  increase  our  weight  200 
per  cent  in  the  first  year,  less  than  30  in  the  second,  only  5 
in  the  fifth.  Increase  in  weight  then  picks  up  again  and 
continues  until  the  tenth  year,  to  drop  back  from  the  eleventh 
to  the  thirteenth.  From  the  fourteenth  to  the  seventeenth, 
puberty  years,  it  increases  again,  to  12  per  cent.  That  is 
our  last  spurt.  It  drops  to  4  per  cent  during  the  eighteenth 
year;  to  1  per  cent  during  the  twenty-second. 

Stature  also  increases  by  spurts.  By  the  time  the  infant 
can  walk,  it  has  grown  from  twenty  to  thirty-four  inches; 
thereafter,  until  puberty,  it  grows  between  two  and  three 
inches  a  year.  The  thirteenth  is  the  rapid  growing  year 
for  girls,  the  sixteenth  for  boys.  Between  fourteen  and 
sixteen  the  boy  increases  his  stature  eight  inches.  Girls 
usually  attain  their  full  stature  by  twenty,  sometimes  by 
eighteen;  boys  by  twenty-five.  But  both  may  continue  growth 
three  or  four  years  longer,  boys  even  up  to  thirty- five. 

The  newborn's  brain  is  already  one-fifth  its  destined  weight, 



about  ten  ounces;  by  the  second  year  two-fifths,  or  as  large 
as  an  adult  anthropoid  ape's.  Full  brain  weight  comes 
before  twenty- five;  after  that  it  loses  weight,  rapidly  in  old 

The  body  changes  proportions  during  growth.  At  twenty- 
five  years  the  middle  point  of  stature  cuts  across  the  pelvis 
— legs  make  up  half  the  total  length;  at  birth,  only  three- 
eighths;  of  a  two-months'  fetus,  only  one-eighth.  Adult  man 
cannot  easily  walk  on  all-fours;  at  birth  he  is  better  pro- 
portioned for  an  all-fours  gait  than  a  gorilla. 

The  two  elements  in  growth  are  weight  and  height.  Weight 
often  continues  beyond  maturity,  long  after  the  body  has 
taken  on  its  last  cubit.  The  giant  can  grow  no  taller;  the 
fat  lady  knows  no  limit. 

In  prenatal  life  weight  increases  by  growth,  division,  and 
growth  of  cells.  A  bacterium  increases  its  weight  by  1,000 
per  cent  in  a  few  hours;  the  human  embryo  at  first  grows 
at  least  as  fast.  Weight  after  birth  increases  in  the  size 
rather  than  in  the  number  of  the  cells  of  the  body. 

Stature  is  determined  almost  entirely  by  the  skeleton.  Only 
skin  and  a  thin  layer  of  fat  cover  skull  and  the  bones  of  the 
feet;  thin  cartilage  covers  the  ends  of  the  leg  bones;  between 
the  vertebrae  are  thin  pads  of  cartilage.  Stature  growth, 
then,  is  largely  a  matter  of  growth  of  skull,  bodies  of  verte- 
brae, and  especially  of  the  leg  bones. 

Bones  grow  from  centers  of  ossification.  Centers  for  the 
principal  bones  of  the  body  appear  by  the  end  of  the  second 
month  of  fetal  life;  centers  for  the  ends,  or  epiphyses,  appear 
later — many  not  until  puberty,  when  the  skeleton  begins  to 
assume  its  permanent  form. 

The  number  of  ossification  centers  varies  in  different  bones. 
The  long  bones  of  the  arms  and  legs  have  at  least  three:  one 
in  the  shaft  itself  and  one  at  each  epiphysis.  The  humerus 
at  fifteen  years  is  still  in  three  parts:  shaft,  two  heads;  but 
the  heads  are  more  closely  connected  with  shaft  than  at  birth. 



By  maturity,  the  heads  are  so  united  with  the  shaft  that  it  is 
not  possible  to  see  where  they  grew  on. 

In  general,  facial  and  skull-dome  bones  are  formed  from 
membrane — "skin"  bones ;  the  other  bones  begin  in  cartilage. 
Bone-forming  cells  multiply  by  division,  absorb  lime  salts 
from  the  blood,  ossify,  and  so  continue  until  the  cartilage  is 
replaced  by  bone.  Increase  in  length  ends  when  the  cartilage 
disappears.  In  the  mature  skeleton  there  can  be  no  further 
growth  in  stature  or  in  length  of  arms.  If  final  conversion 
of  cartilage  to  bone  is  delayed,  gigantic  stature  results ;  if  the 
process  is  reversed,  dwarfs.  Only  the  articulating  or  joint 
surfaces  of  mature  bones  are  covered  by  cartilage. 

Bones  increase  in  girth  by  additions  of  bone  cells  from  the 
surrounding  membrane.  Long  bones  are  hollow.  To  pre- 
serve their  relative  proportion  of  bone  wall  to  cavity,  bone 
cells  on  the  inside  are  destroyed  as  fast  as  cells  are  added  to 
the  outside.  Thus  the  cavity  grows  with  the  bone,  the  form 
and  strength  of  the  bones  are  preserved.  This  process  keeps 
up  until  late  in  life.  With  old  age  the  bones  become  thin 
and  delicate. 


Complicated  changes  take  place  in  acquiring  the  upright 
gait.  A  chick  can  run  from  its  shell;  a  baby  cannot  even 
straighten  its  legs.  They  bend  in  at  the  knees  and  are  drawn 
up  at  the  hips,  and  are  only  60  per  cent  of  head-trunk  length. 
By  maturity  they  will  be  over  100  per  cent.  As  the  walking 
days  approach,  the  legs  grow  fast.  Knee  and  hip  joints 
change;  the  legs  can  now  be  straightened  out.  The  soles  of 
the  feet  no  longer  turn  in.  The  baby  at  birth  can  clap  its  feet 
almost  as  easily  as  its  hands. 

The  spine  also  changes.  It  is  not  solid,  but  consists  of 
twenty-four  vertebrae  with  pads  of  cartilage  between.  At 
birth  a  large  percentage  of  the  column  is  cartilage.  Power- 
ful muscles  develop  to  hold  the  spine  erect;  others,  acting  on 



the  ribs  as  levers,  to  balance  the  trunk  and  spine.  The  last 
five,  or  lumbar,  vertebrae  at  birth  make  up  27  per  cent  of 
the  total  spine  length,  as  in  adult  chimpanzees ;  in  adults  they 
make  up  32  per  cent.  The  first  two  lumbar  vertebrae  take 
on  their  wedge  shape  which  produces  the  curve  in  the  small 
of  our  back  only  after  birth.  When  the  baby  first  tries  to 
stand,  it  bends  backward  at  the  loins. 

Standing  is  a  complex  act  involving  nearly  all  our  big 
muscles.  When  we  stand  "at  attention,"  powerful  ligaments 
in  the  hip  joint  hold  the  body.  This  relieves  the  muscles  from 
strain,  but  locks  the  knee  joint.  We  stand  easier  if  the  knees 
are  slightly  bent  and  the  knee-caps  loose. 

The  feet  muscles  must  bind  the  many  small  bones  together 
to  give  support  and  form  the  instep  or  arch.  A  man  can 
stand  up  asleep,  but  not  if  muscles  of  feet  or  of  legs  are 

In  walking,  each  leg  rests  half  the  time.  We  tire  standing 
because  neither  leg  gets  rested.  The  shoulder  muscles  which 
hold  the  head  erect  also  ache  from  the  strain  in  standing.  As 
we  nap  in  a  chair  the  head  nods. 

Flat  feet  are  not  due  to  a  giving  way  of  ligaments;  liga- 
ments limit  joint  movement.  Feet  become  "flat"  when  the 
muscles  of  the  arch  fail  to  support  it;  the  arch  breaks  down. 
The  result  is  a  mid-tarsal  joint.  This  is  most  likely  to  happen 
in  long,  narrow  feet. 

Short  feet  and  high  insteps  go  with  large  calves.  To  raise 
our  body  on  our  toes,  we  lift  our  heel.  The  toes  are  the 
fulcrum,  the  power  is  the  calf  muscles;  the  weight  falls  on 
the  foot  at  the  ankle  joint  but  nearest  the  power  at  the 
heel.  Hence  the  greater  need  for  large  calf  muscles.  But 
small  calves  go  with  long  heel  bones.  As  the  foot  is  a 
lever  of  the  second  order,  the  long  heel  brings  the  weight 
nearer  the  fulcrum — that  is,  the  toes.  Hence  "flat-foots"  do 
not  step  off"  their  toes;  the  fallen  arch  destroys  the  lever  of 
the  foot. 

We  nod  our  head  between  skull  and  first  vertebra,  or  atlas ; 



rotate,  between  atlas  and  second  vertebra,  or  axis.  Both 
movements  are  limited  by  ligaments;  otherwise  the  spinal 
cord  would  be  crushed. 

The  main  business  of  the  face  is  to  hold  the  teeth-bearing 
jaws;  eyes  and  nose  moved  in  by  accident.  The  infant's 
face  and  neck  seem  small  because  the  brain  is  so  large. 
Their  real  growth  begins  with  the  eruption  of  the  teeth. 

The  skull  is  a  fulcrum  for  the  jaw  muscles  in  chewing. 
Muscles  to  hold  the  fulcrum  steady  develop  with  the  teeth. 
The  neck  grows  larger.  With  the  teeth  all  in  place  the 
neck  reaches  normal  size,  the  rounded  "baby-face"  disap- 
pears; strong  jaws,  powerful  muscles,  and  prominences  and 
ridges  on  bones  of  face  and  head  support  the  muscles  of 
mastication.  The  tiny  mastoid  processes  below  the  infant's 
ears  become  adult  structures  as  big  as  thumbs,  required  for 
muscle  support. 

The  first,  or  milk,  teeth  should  be  in  place  by  the  end  of 
the  second  year.  Meanwhile  the  transverse  ridges  in  the 
roof  of  the  infant's  mouth  disappear.  The  permanent  denti- 
tion begins  with  the  first  molars  in  the  seventh  year;  incisors 
in  the  eighth  and  ninth;  premolars  in  the  tenth  and  eleventh; 
canine  and  second  molars  in  the  thirteenth  to  fourteenth ;  third 
molars,  or  wisdom  teeth,  in  the  seventeenth  to  fortieth  year. 

Startling  changes  of  far-reaching  consequence  mark  the 
years  of  adolescence  for  both  sexes.  As  these  changes  are 
both  physical  and  mental,  and  as  they  proceed  under  impulses 
from  the  gonads  acting  as  glands  of  internal  secretion,  they 
will  be  described  in  the  chapter  devoted  to  the  endocrine 

After  maturity  the  body's  chief  task  is  to  maintain  its 
equilibrium:  produce  enough  energy  and  heat  to  keep  up 
repairs  and  carry  on.  But,  from  ovum  to  death,  the  body 
never  ceases  to  change.  Senility  may  be  postponed;  the 
body  begins  to  age  the  day  the  ovum  begins  to  grow.  Before 
the  newborn  can  mature,  it  must  grow  more  human.  Before 



it  is  twenty  years  old,  it  will  increase  its  weight  from  fifteen 
to  thirty  times.    Thereafter  it  grows  old  at  a  less  rapid  rate. 

Old-age  or  senile  changes  precede  natural  death.  These 
appear  toward  the  end  of  a  span  of  life  which  varies  in  differ- 
ent species.  This  span  of  life  for  some  invertebrates  is  less 
than  100  hours;  for  some  insects,  17  years;  for  some  fishes 
and  reptiles,  over  200  years;  for  some  birds  and  mammals, 
120  years. 

Absolutely  authenticated  cases  of  human  beings  alive  be- 
yond 100  years  are  almost  unknown.  It  is  far  from  certain 
that  Thomas  Parr  lived  152  years.  A  critical  examination 
of  nearly  one  million  cases  of  alleged  unusual  longevity 
showed  none  over  100,  and  only  thirty  that  lived  that  long; 
twenty-one  were  women. 

Longevity  is  not,  as  Weismann  claimed,  related  to  size  of 
body.  Some  mammals  live  less  than  two  years,  some  locusts 
seventeen.  A  dog  is  old  at  20.  I  have  seen  a  parrot  117 
years  old;  it  matured  in  its  first  year.  A  tortoise  can  live 
350  years.  No  elephant  known  has  exceeded  130  years. 
Nor  does  death  "naturally"  follow  the  reproductive  stage; 
innumerable  animals  long  survive  their  sex  life.  But  every 
animal  must  reach  sex  maturity  or  its  kind  dies  with  it. 

Old  age  is  decrepitude;  the  body  is  worn  out.  The  mechan- 
ism the  infant  acquired  to  walk  with  breaks  down.  The  spine 
is  not  so  supple,  the  cartilage  disks  between  vertebrae  shrink. 
This  decreases  stature — as  much  as  three  inches  after  fifty. 
The  spine  both  collapses  and  "stoops  with  age."  The  knees 
are  bent,  the  hip  joints  stiff.  The  muscles  shrink.  The  body 
loses  its  natural  fat.  Folds  of  skin  appear  on  neck  and 
face.  The  toothless  jaws  atrophy  and  the  mouth  loses  its 
shape.  Cheeks  and  temples  cave  in,  the  bony  scaffold  be- 
neath stands  out. 

The  brain  loses  weight — in  the  last  forty  years  of  life  as 
much  as  three  ounces.  The  heart  is  enlarged  from  over- 
action  to  keep  the  blood  coursing  through  thick,  hard  arteries. 
The  pulse  mounts  again.    It  was  134  at  birth,  110  at  the 



end  of  the  first  year,  72  at  twenty-one.  After  eighty,  it  is  80. 
The  lungs  lose  their  elasticity,  the  walls  become  thicker. 

Many  women  after  fifty  show  a  thicker  neck,  hair  on  the 
face,  deeper-toned  voice,  more  prominent  cheek-bones,  ridges 
over  the  eyes.  Their  "feminine"  traits  are  less  feminine.  It  is 
as  though  the  inactivity  of  the  gonads  permitted  a  return  to  a 
neutral  condition,  halfway  between  male  and  female. 

Old  age,  senility,  decrepitude;  the  body  is  worn  out,  it  can 
no  longer  function.  Death. 


There  are  no  two  human  beings  quite  alike;  every  human 
being  in  the  world  is  unique.  And  yet  there  are  about  seven- 
teen hundred  million  beings  in  the  world  to-day  so  much 
alike  in  body  and  behavior  that  without  hesitation  we  call 
them  human;  they  all  belong  to  the  human  race.  Nor  is 
there  any  doubt  about  the  striking  physical  differences  be- 
tween a  white-skinned,  blue-eyed,  fair-haired  Scandinavian 
and  a  black-skinned,  black-eyed,  frizzly-haired  Senegambian. 
The  Scandinavian  and  the  Senegambian  are  so  different  that 
they  could  not  possibly  be  mistaken  one  for  the  other.  Do 
they  belong  to  the  same  race? 

Recently  I  came  across  this  heading:  "Races  Now  Well 
Defined";  and  here  is  a  sample  definition:  ''Asiatic  or  Mon- 
golian race — yellowish  color,  dark  hair  and  brown  eyes, 
character  cruel  and  avaricious,  fond  of  show,  likes  to  dress 
in  flowing  garments,  and  is  ruled  by  prevailing  opinions!" 
This  is  sheer  nonsense.  Here  is  a  better  one:  ''Caucasian  or 
European  race — white  skin,  red  cheeks,  brown  hair,  round 
skull,  oval  face,  smooth  forehead,  narrow  nose,  small  mouth, 
perpendicular  front  teeth,  face  symmetrical;  and  agreeable." 
Agreeable  race,  therefore! 

Most  of  this  confusion  dates  from  Blumenbach's  scheme 
of  five  races,  one  for  each  continent.  But  as  a  matter  of  fact 
no  anthropologist  knows  where  "Caucasian"  leaves  off,  where 



"Mongolian"  begins.  Boas,  our  foremost  anthropologist,  once 
addressed  a  Japanese  in  an  Indian  tongue  of  the  northwest 
coast  of  America — ^he  thought  the  Jap  a  native  American!  I 
could  pick  a  dozen  old  women  out  of  Peking,  dress  their 
hair  and  put  them  in  beaded  buckskin,  and  defy  Congress  to 
tell  whether  they  are  Arapaho,  Manchu,  Chinese,  or  "Mon- 

is  a  biologic  term  and  has  to  do  with  physical 
characters  based  on  blood  relationship.  The  extent  to  which 
environment  may  alter  the  physical  features  we  are  born  with 
is  still  an  unsolved  problem.  There  is  no  Aryan  or  Semitic 
race,  because  "Aryan"  and  "Semitic"  are  linguistic  terms  and 
refer  to  peoples  who  learn  to  speak  an  Aryan  or  Semitic 
dialect.  In  other  words,  race  is  the  naked  body  we  are  born 
with;  language  and  culture,  the  duds  we  learn  to  wear — often, 
in  civilization,  with  much  discomfort.  There  are  varieties 
or  types  of  men  on  the  one  hand ;  on  the  other,  groups,  tribes, 
nations,  having  a  common  language  or  a  common  culture  or 
both.  To  classify  people  by  language  or  culture  is  one  thing; 
to  classify  man  by  physical  traits  is  quite  another. 

There  are  Negroes  in  America  of  African  ancestry;  they 
speak  English,  are  civilized,  Christian,  American.  Trans- 
plant them  to  Africa:  they  cannot  get  rid  of  their  physical 
features;  they  may  forget  or  retain  their  English  or  acquire 
a  new  tongue — or  a  half-dozen ;  they  may  retain  their  "civili- 
zation"; they  may  become  Mohammedans  and  adopt  Arabic 
culture;  or  they  may  become  cannibals  and  found  a  slave- 
trading  kingdom. 

A  man's  great-grandmother  may  have  been  Indian,  his 
other  ancestors  mixed  Irish,  Swedish,  Spanish,  and  Turkish: 
that  man  is  white,  Caucasian,  Aryan,  and  may  be  "Nordic." 
For  "Indian"  substitute  "Negro";  if  any  of  the  Negro  shows 
through,  he  is  a  Negro!  This  gives  us  the  emotional  element; 
prejudice  is  at  work.  Clothes  and  the  barber  go  far  to 
make  the  man,  but  prejudice  trains  the  eye  to  detect  signs  that 



would  otherwise  never  be  noticed.  A  Negro  of  Atlanta  is 
often  a  white  north  of  Dixie. 

The  emotional  factor  takes  it  for  granted  that  moral  and 
intellectual  values  inhere  in  skin  color,  language,  culture, 
and  nationality.  H.  G.  Wells's  heart  beats  faster  in  nearly 
every  chapter  of  his  Outline  of  History,  because  he  cannot 
forget  that  he  is  Nordic,  Aryan,  English,  British,  white,  civi- 
lized. Are  these  traits  innately  or  necessarily  related? 

Assuming,  as  every  biologist  does,  that  man's  ancestor  was 
a  monkey  before  he  was  an  ape,  is  the  blond  Caucasian  a 
"higher"  type  than  the  dark  Ethiopian?  Is  one  the  end,  the 
other  the  beginning,  of  human  evolution?  In  other  words, 
are  there  higher  and  lower  races?  Common  sense  says  "yes." 
Common  sense  also  said:  There  are  ghosts.  Witches  turn 
milk  blue.    Any  idiot  can  see  that  the  earth  is  flat! 

If  I  measure  by  my  foot  and  weigh  by  my  body,  I  can 
grade  the  whole  human  race  from  myself  down  to  the  lowest, 
blackest  Pygmy.  Man  is  usually  measured  and  weighed  that 
way,  and  with  the  same  result:  "high";  "low."  The  "highest" 
are  the  whitest;  the  "lowest,"  blackest:  when  the  grader  is 
white.  It  is  good  psychology — self-love  is  the  first  law  of 
life — but  not  good  biology.  Imagine  dogs  graded  from 
"high"  to  "low"  by  a  Pekinese  pug,  a  Mexican  hairless,  a 
Scotch  collie,  an  Australian  dingo;  or  pigeons  graded  by  a 
pouter,  a  carrier,  a  fantail,  a  tumbler,  a  rockdove! 

Color  probably  has  no  biologic  significance;  it  may  have 
physiologic  value.  Nowhere  in  the  plant  or  animal  world 
is  it  a  mark  of  high  or  low,  or  of  progressive  or  backward. 
Man's  skin  color  is  partly  determined  by  exposure,  mostly 
by  an  inherited  mechanism  which  regulates  pigment.  How 
or  why  this  mechanism  works,  how  it  arose  and  why  it  varies 
as  it  does  in  man,  we  do  not  know. 

Pigment  is  probably  a  waste  product  of  cell  metabolism;  it 
contains  iron;  it  is  possibly  a  response  to  living  tissue's  need 
for  protection  from  harmful  light  rays.  This  does  not  help 
much.  Why  are  Eskimos  brunettes,  Icelanders  blonds?  Wliy 



are  the  Amazon  forest  natives  "red,"  those  of  the  Niger 
forests  black? 

All  humans  (except  albinos)  have  skin  pigment;  it  is  the 
amount  that  counts.  A  white  skin  may  turn  dark  bronze  in 
Addison's  disease.  White  skins  develop  black  moles  and 
tumors,  and  even  general  melanosis — dark  pigment  is  carried 
by  the  blood  and  deposited  throughout  the  body. 

Much  is  known  of  man's  anatomy  at  the  dawn  of  the 
human  race;  the  color  of  his  skin  and  other  details  are  not 
known.  Fossil  bones  tell  a  story;  they  supply  "links";  they 
may  help  clothe  the  skeleton  with  flesh,  but  not  with  skin 

Our  ancestral  skin  was  probably  dark.  The  amount  of 
pigment  increased  in  the  Negroid  type,  decreased  in  the 
Mongoloid.  They  represent  the  two  extremes.  But  "high" 
and  "low"  skin  color  is  as  sound  biology  as  grading  planets 
by  color  would  be  sound  astronomy:  Venus  "highest"  be- 
cause whitest! 

Kinky  wooly  hair  is  found  in  no  apes  or  monkeys;  straight 
black  hair  is.  The  kink  is  the  "highest"  type,  the  straight 
black  the  "lowest."  Where  shall  we  put  the  red — and  the 

The  African's  jaws  are  heavy:  they  support  a  first-class 
set  of  teeth.  The  European  goes  to  the  dentist  to  have  his 
jaws  stretched;  high — or  merely  degenerate?  The  Negro 
scores  with  his  thick  out-turned  lips;  no  men  in  the  world 
have  such  human  lips  as  the  blackest  Africans.  Thin  lips 
are  primitive — "low,"  apish.  Even  in  the  bony  ridges  above 
the  eyes,  most  Negroes  are  among  the  "highest"  of  man. 
This  ridge  is  extraordinarily  developed  in  the  gorilla;  also 
among  the  blacks  of  Australia.  But  in  the  gorilla  it  is  a 
secondary  sexual  character.  It  is  not  found  in  gorilla 
children,  nor  at  all  in  gibbons  of  either  sex. 

The  earliest  human  skulls  were  probably  long.  Negro 
skulls  are  long,  but  not  so  long  as  the  Eskimo.  There  are 
round  heads  in  Europe;  rounder,  in  China.    There  is  no 



evidence  that  big  brains  are  innately  associated  with  long  or 
with  round  heads;  nor  any  evidence  that  extreme  artificial 
deformation  of  infants'  skulls  (a  widespread  custom) 
changes  the  size  of  the  brain  or  the  capacity  for  intelligent 

In  brain  weight,  the  average  of  a  hundred  Europeans  would 
slightly  exceed  the  average  of  a  hundred  Africans,  but 
among  the  Africans  many  will  be  found  exceeding  the  Euro- 
pean average.  The  two  groups  overlap;  no  sharp  line  can 
be  drawn.  Nor,  after  diligent  search,  has  any  difference 
been  found  in  brain  structure  or  in  convolutions.  Intelli- 
gence does  not  depend  on  size  of  skull,  nor  is  a  big  skull  any 
proof  of  ability.  Neanderthal  man  of  fifty  thousand  years 
ago  had  a  bigger  skull  than  we  have;  he  disappeared. 

The  Negro's  lumbar  vertebrae  are  of  a  primitive  type;  his 
gait  is  as  upright  as  the  European's.  His  spine  retains 
more  of  its  original  suppleness. 

The  Negro's  nose  is  primitive ;  it  would  not  be  so  primitive 
if  he  had  less  jaw.  The  more  the  jaws  recede,  the  more 
prominent  the  nose.  If  a  low-bridge  nose  is  "low,"  the 
"highest"  bridge  comes  from  Asia,  through  the  Jews,  acquired 
from  the  Hittites. 

In  long  arms  as  compared  with  leg  length,  the  African  is 
more  primitive  than  the  European;  as  he  is  in  his  longer 
heel  and  smaller  calves.  In  size  and  shape  of  external  ear, 
he  is  less  primitive  than  the  European. 

What  is  it  all  about,  then?  Much  of  it,  convictions;  habits 
of  mind;  prejudices,  emotionally  reinforced.  There  are 
dozens,  perhaps  hundreds,  of  physical  types.  Some  have 
peculiarly  or  excessively  marked  features  in  one  direction, 
some  in  another.  To  have  diverged  from  the  parent  type 
means — simply  divergence.  We  read  significance  into  color 
of  skin  and  other  physical  traits  without  knowing  the  facts 
behind  these  traits  or  the  causes  of  change.  There  is  no 
known  fact  of  human  anatomy  or  physiology  which  implies 



that  capacity  for  culture  or  civilization  or  intelligence  inheres 
in  this  race  or  that  type. 

How  about  the  "Nordics,"  then?  How  comes  it  that  the 
Anglo-Saxon  is  at  the  top  of  the  heap?  Is  it  not  because  of 
his  inherited  ability  that  he  rides  the  wave?  The  answer  is 
to  be  found  in  the  cultural  history  of  man.  What  wave  did 
the  Anglo-Saxon  ride  in  the  days  of  Tut-ankh-Amen,  or  of 
Caesar,  or  of  William  the  Conqueror?  Are  his  feet  riveted 
to  the  crest? 

Civilization  is  young;  blood  is  as  old  as  salt  water.  Once 
there  was  no  Anglo-Saxon;  but  there  was  "civilization." 
Were  there  "higher"  and  "lower"  races  then?  How  "low" 
the  savage  European  must  have  seemed  to  the  Nile  Valley 
African,  looking  north  from  his  pyramid  of  Cheops! 

Divergence,  mixture ;  in  isolated  spots  more  divergence,  less 
mixture;  and  so,  sharply  defined  types — as  the  Eskimo.  No 
people  have  a  more  distinct  physical  type  than  they  have.  I 
know  of  no  skull  more  specialized  or  more  easily  distinguish- 
able in  a  collection  of  skulls  than  an  Eskimo's.  They  are 
"pure."  Perhaps  no  people  living  are  purer!  No  one  pre- 
tends that  there  is  an  Eskimo  race. 

"Pure"  types  are  extreme  types.  Blue  eyes,  flaxen  hair, 
white  skin,  is  an  extreme  type.  The  huge  African  with  kinky 
hair,  black  skin,  thick  lips,  high  smooth  brow,  hairless  body, 
is  equally  extreme.  One  is  as  pure  as  the  other;  one  is  as 
high  as  the  other. 

Huxley  classified  man  by  hair;  he  was  too  good  a  zoologist 
to  classify  cats  by  hair.  Hair  is  only  hair.  Its  color  is  one 
thing,  due  to  pigment;  its  shape  is  another.  Straight  hair 
in  cross  section  is  round;  kinky  hair,  flattish.  There  is 
straight  black  hair,  black  hair  that  will  not  stay  straight,  and 
curly  hair  from  red  to  black. 

We  know  too  little  yet  what  environmental  change  does  to 
physical  structure,  too  little  of  the  permanence  of  types,  too 
little  of  the  causes  of  change  of  type.  We  have  no  classi- 
fication of  man  based  on  stature,  skin  color,  hair  form,  head 



form,  proportions  of  limbs,  etc.,  so  correlated  that  they  fit 
one  race  and  one  only.  The  original  divisions  of  the  human 
race  are  not  yet  known.  Possibly  they  never  will  be  known; 
possibly  there  were  no  grand  divisions;  possibly  only  minor 
types  developed  from  time  to  time.  Some  of  these  types 
became  extinct  or  left  only  traces  which,  through  intermar- 
riage, have  become  so  hopelessly  mixed  that  they  can  no 
longer  be  distinguished. 

Nature  is  not  so  prejudiced  as  we  are.  She  says  that  there 
is  a  human  race,  that  all  human  beings  are  of  the  same 
genus  Homo,  species  sapiens.  She  draws  no  color  line  in  the 
human  or  in  any  other  species.  Black  and  white  dogs  mix  as 
readily  as  do  blacks  and  whites  when  the  sex  impulse  is  not 
outlawed,  and  are  equally  fertile. 

In  biology,  fertility  is  generally  regarded  as  a  criterion  of 
species.  Using  "race"  as  S3nionymous  with  "species,"  man  is 
of  one  race.  Hence  the  difficulty  in  distinguishing  even  sub- 
species, subraces,  varieties,  and  types  of  men;  they  overlap. 
The  human  species  has  interbred.  There  are  no  biologically 
pure  varieties  and  certainly  no  pure  races,  except,  possibly, 
the  Pygmy. 


Open  your  atlas  to  a  map  of  the  world.  Look  at  the 
Indian  Ocean:  on  the  west,  Africa;  on  the  north,  the  three 
great  southern  peninsulas  of  Asia;  on  the  east,  a  chain  of 
great  islands  terminating  in  Australia.  Wherever  that  Indian 
Ocean  touches  land,  it  finds  dark-skinned  people  with  strongly 
developed  jaws,  relatively  long  arms,  and  kinky  or  frizzly 
hair.  Call  that  the  Indian  Ocean  or  Negroid  division  of  the 
human  race. 

Now  look  at  the  Pacific  Ocean:  on  the  one  side,  the  two 
Americas;  on  the  other,  Asia.  (Geographically,  Europe  is  a 
tail  to  the  Asiatic  kite.)  The  aboriginal  population  of  the 
Americas  and  of  Asia  north  of  its  southern  peninsula  was  a 



light-skinned  people  with  straight  hair,  relatively  short  arms, 
and  a  face  without  prominent  jaws.  Call  that  the  Pacific 
Ocean  or  Mongoloid  division. 

This  grouping  of  man  into  two  grand  divisions  was  pro- 
posed by  Boas.  The  scheme  has  the  merit  of  convenience 
and  is  based  on  facts.  Almost  every  shade  of  skin  color  can 
be  found  in  India.  But  the  early  inhabitants  of  India  were 
black.  Their  descendants  survive  to-day  on  many  isolated 
peaks  of  Central  India.  They  have  Negroid  faces,  dark 
skin,  woolly  hair.  In  the  Malay  Peninsula  and  the  Philippine 
Islands  are  isolated  bands  of  little  blacks  or  Negritos.  The 
blacks  have  disappeared  from  Java,  and  in  Sumatra  have 
left  only  a  tinge.  The  natives  of  Australia  are  black,  as 
were  those  of  Tasmania.  The  Melanesian  Islands  north  of 
Australia  are,  as  their  name  implies,  peopled  with  blacks. 

Negroes  did  not  get  their  skin  pigment  from  any  "mark" 
put  on  Cain.    Bible  and  biology  are  silent  on  Cain's  color.  ^ 
Biologically  speaking,  the  white  skins  of  North  Europe  havef 
lost  something.   When  or  where  they  lost  their  pigment,  and| 
why  they  lost  more  than  the  Asiatics,  we  may  never  know.j 
But  they  have  lost  enough,  in  Kroeber's  opinion,  to  suggest 
that  to  Boas's  Negroid  and  Mongoloid  divisions  a  third 
should  be  added — the  Caucasian. 

Kroeber  distinguishes  four  subtypes:  Nordic,  Alpine,  and 
Mediterranean  in  Europe,  and  Hindu  in  Asia.    What  are 
the  facts?  In  general,  skin  color  deepens  and  stature  dimin- 
ishes in  Europe  from  north  to  south.    North  Germans  are 
Nordic;  South  Germans,  Alpine.    Tjie  Alpine  is  broad- 
headed;  the  others,  long.    The  Hindu  is  long-headed  and 
dark-skinned,  probably  due  to  mixture  with  the  submerged 
aborigines.    Otherwise  we  have  not  moved  a  foot.    It  can 
as  easily  be  shown  that  between  North  Europe  and  India 
there  are  only  three  subtypes — or  that  there  are  thirty-three. 
[  You  can  have  as  many  as  you  like.   To  use  William  James's 
I  figure,  counting  "subtypes"  is  as  profitable  as  counting  the 
I  stones  on  a  New  Hampshire  farm.    But  if  any  Nordic's 



pride  is  soothed  by  recognizing  a  Caucasian  division  and 
four  subtypes,  let  it  be  soothed. 

The  prevailing  color  of  the  Mongoloid  type  is  yellow. 
Malays  and  American  Indians  are  nearest  to  the  original 
type.  The  Chinese  are  a  divergent  strain;  the  Eskimo,  a 
peculiar  subvariety.    The  Negroid  type  abounds  to-day  in 

Africa  proper  (south  of  the  Sahara)  and  in  Melanesia.  | 

Millions  of  Europeans  are  darker  in  color  than  millions  i 
of  Asiatics.    The  colors  overlap  along  the  borders;  they  j 
will  intermarry.    The  border  itself  is  a  political  boundary,  j 
not  a  racial  barrier.    North  Europeans  were  not  always 
as  colorless  as  they  are  now.    Once  there  was  neither  Mon- 
goloid nor  Negroid.   These  divisions  simply  represent  direc- 
tions of  development,  probably  begun  on  two  continents —  | 
Asia,  Africa.    Some  diverged  from  the  main  line  before  ! 
others;  their  affiliations  cannot  be  made  out. 

For  example,  the  Bushmen  and  Hottentots  of  South  Africa  ! 

are  two  distinct  Negroid  subtypes;  yet  they  are  also  distinct  j 

from  typical  blacks.    Both  are  yellowish  in  color,  have  long  I 

heads,  short  flat  ears,  short  legs.  Are  they  remnants?  Of  | 

what?  I 

African  Negroes  and  Melanesians  of  the  South  Pacific  i 

are  close  kin.    The  African  has  a  flat  nose,  the  Melanesian  i 

aquiline.  Why  is  the  Fijian  black,  his  nearest  neighbor  i 

The  Australian  black  is  a  puzzler.    In  some  ways  he  is  i 

nearer  Caucasian  than  Negroid.    He  is  short,  slender,  long-  j 

headed;  has  a  broad  nose,  wavy  hair.    His  closest  kin  are  i 

the  primitive  folk  of  South  Asia :  Kolarians  of  India,  Veddas  i 

of  Ceylon,  Sakai  of  the  Malay  Peninsula;  the  group  is  often  i 

called  the  Indo-Australian.    Possibly  the  Veddas  branched  J 

from  the  Caucasian  type  before  it  lost  its  pigment  and  took  J 

on  the  European  type  of  face.  | 

The  Negritos,  or  Pygmies,  are  even  more  puzzling.    The  S 

average  stature  of  the  human  race  is  five  feet  five  inches,  i 

Few  groups  of  men  vary  from  this  more  than  two  inches.  No  i 

46  j 


race  averages  less  than  five  feet  or  more  than  five  feet  ten 
inches  except  the  Pygmies  of  equatorial  Africa,  the  Malay 
Peninsula,  New  Guinea,  and  the  Philippine  Islands;  they 
are  true  dwarfs.  Their  average  stature  is  a  full  foot  short 
of  the  average  of  that  of  man.  Many  adult  Pygmies  are 
only  four  feet;  no  males  exceed  five  feet.  If  stature  were 
held  to  be  a  mark  of  race,  there  would  be  only  two  races — 
Pygmy;  non-Pygmy. 

The  Pygmies  are  as  black  as  blacks;  they  are  dwarfs;  other- 
wise they  are  as  human  as  Nordics.  In  jaws,  lips,  and  nose, 
they  are  more  Nordic  than  African;  in  relative  length  of  arm 
to  leg  they  are  almost  as  close  to  the  Chimpanzee  as  the  true 

The  Pygmies  are  spread  around  a  quarter  of  the  globe. 
They  are  so  alike  in  physical  type  that  they  constitute  a  real 
thorn  in  unraveling  the  history  of  man's  body.  They  com- 
plicate the  general  problem  of  human  races;  they  constitute 
a  distinct  problem  in  themselves.  Are  they  remnants,  heritors 
of  the  ape  crowd  that  left  the  trees  for  good?  Possibly. 
Theirs,  perhaps,  is  the  type  of  body  our  ancestors  tried  out 
ages  ago.  It  was  good  enough  to  be  human  and  to  survive; 
it  was  not  good  enough  to  subdue  the  earth. 

Two  points  seem  to  stand  out  over  and  above  every  dis- 
cussion of  races  and  varieties  of  man:  there  are  areas  of 
characterization — within  such  areas,  especially  if  isolated 
for  long  periods,  certain  physical  traits  or  varieties  become 
pronounced;  these  physical  traits  or  varieties  are  neither 
necessarily  biologically  useful  nor  related  to  mental  capacity 
or  intellectual  endowment. 


Unless  well  protected,  or  in  rainless  Peru  or  Egypt,  or  in 
dry  caves,  or  the  cold  storage  of  Arctic  ice,  or  in  oil,  wax, 
or  amber,  the  body  soon  yields  to  the  bacteria  of  decay  or  to 
the  teeth  of  wolves  and  hyenas.    For  bone  or  other  tissue  to 



be  replaced  by  mineral  v/hereby  it  petrifies  or  "fossilizes," 
many  conditions  must  be  right.  The  wiser  the  animal,  the 
less  likelihood  of  its  being  caught  in  quicksands  or  en- 
gulfed by  the  gravel  and  silt  of  floods.  Primitive  man  was 
as  little  enamored  as  we  are  of  being  buried  alive. 

Fossil  remains  of  the  famous  Cro-Magnon  man  have  been 
found  in  Wales,  and  especially  in  France.  Possibly  earth 
never  saw  finer  built  human  beings.  His  brain  was  15  per 
cent  larger  than  ours,  his  stature  taller  than  any  living  race 
by  two  inches.  He  was  clean-limbed,  lithe,  and  swift.  He 
had  a  good  chin,  thick  and  strong  jaws.  His  head  was  long, 
his  face  broad.  He  buried  his  dead.  He  was  an  artist  and 
an  artisan.  He  lived  about  25,000  years  ago.  Did  he  be- 
come an  ordinary  European,  or  did  he  disappear?  No  one 

Beyond  Cro-Magnon,  our  forbears  rather  run  to  brutish 
casts.  Grimaldi  man  was  of  the  Negroid  type.  Neanderthal 
man  had  a  huge  head,  chipped  flint,  and  buried  his  dead.  He 
is  set  down  at  50,000  B.  C.  and  left  no  known  heirs.  He 
is  the  first  known  cave-man. 

The  jaw  of  Heidelberg  man  fits  a  gorilla,  but  the  teeth 
are  ours.  He  is  possibly  400,000  years  old.  Piltdown  man 
is  possibly  a  hundred  thousand  years  older.  Some  think  he 
was  an  ape.  Some  say  he  was  the  first  Englishman.  We  have 
reached  a  point  in  time  where  no  one  knows  who's  who. 

The  champion  fossil  is  Pithecanthropus  erectus  (ape-man 
erect),  discovered  by  Dubois  in  Java  in  1891.  He  is  cer- 
tainly a  half -million  years  old;  some  say  a  million.  He  is 
more  pithecoid  than  any  known  human  being,  more  anthro- 
poid than  any  known  ape.  He  was  as  erect  and  almost  as 
tall  as  the  average  European.  He  had  definitely  left  the 
"well-ventilated  arboreal  tenements."  He  was  a  low-browed 
moron — and  may  be  represented  in  the  living  flesh.  But 
whether  he  was  of  the  direct  line  that  led  to  man,  or  only  of 
a  line  that  ended  with  himself,  is  not  yet  definitely  known. 
It  is  enormously  significant  that,  after  a  debate  lasting  more 



than  a  quarter  of  a  century,  the  biologists  of  the  world  can- 
not decide  whether  Pithecanthropus  erectus  belongs  to  the 
first  or  the  second  of  the  earth's  First  Families.  That  makes 
him  a  pretty  good  link  that  is  no  longer  missing. 


There  are  six  families  of  Primates,  premier  order  of 
mammals:  1.  Lemuridae  (lemurs);  2.  Hapalidae  (marmo- 
sets) ;  3.  Cebidae  (monkeys) ;  4.  Cercopithecidae  (baboons, 
monkeys,  etc.  ) ;  5.  Simiidae  (manlike  apes) ;  6.  Hominidae 

To  import  monkeys  for  their  sex  glands  is  ghastly  busi- 
ness, perhaps  the  lowest  that  has  engaged  the  cupidity  and 
lust  of  man,  but  to  shoot  down  simians  as  we  do  mad  dogs  or 
boys  in  uniform  is  a  crime.  The  four  Anthropoid  apes  are 
our  next-of -kin-living;  they  should  be  respected  as  cousins 
and  not  exterminated  as  vermin  or  Indians. 

Man  never  was  a  gorilla,  a  chimpanzee,  an  orang,  or  a 
gibbon.  No  biologist  ever  made  such  a  claim.  Whether  these 
apes  could  have  developed  into  human  beings  is  a  different 
story.  They  have  the  makings — all  the  parts.  If  we  knew 
how  heredity  works  and  could  control  variation,  we  might 
breed  from  an  ape  a  being  that  could  dig  a  ditch,  play  the 
piano,  talk  English,  and  sing  the  "Messiah."  We  can  teach 
them  to  smoke  cigarettes,  chew  tobacco,  drink  beer,  wear 
clothes,  and  eat  with  a  knife  and  fork.  We  do  not  yet 
know  the  limit  of  their  capacity  to  learn  human  ways. 

Why  do  zoologists  put  these  four  apes  so  close  behind  us 
that  we  can  feel  their  breath  and  they  can  catch  our  dis- 
eases? Because  they  are  Anthropoid.  Nothing  has  yet  sur- 
passed them  in  the  race  to  become  human.  Their  anatomy,  em- 
bryology, histology,  morphology,  paleontology,  physiology, 
and  psychology  entitle  them  to  second  place  in  the  Ancient 
and  Honorable  Order  of  Firsts. 

They  vary  in  their  man-likeness;  no  one  is  in  all  ways 



closest  to  man.  The  orang  looks  like  an  Irishman ;  the  gorilla 
is  built  like  Jack  Dempsey;  the  chimpanzee  is  the  most 
angelic;  tlie  delicate  gibbon  has  a  lady-like  skull  and  an  up- 
right carriage.  The  first  three — ^the  Great  Apes — are  the 
extremes  of  variation  from  a  generalized  ancestor.  The 
gibbon  varies  least,  and  to  that  extent  is  nearest  the  tree 
man  climbed  down  when  he  decided  to  stand  up  and  talk. 

Except  in  teeth,  the  young  female  gorilla  is  the  most 
human.  Her  father  is  a  brute  in  size  and  appearance.  Only 
five  feet  high,  he  may  weigh  over  400  pounds:  mostly  neck, 
chest,  and  arms.  If  his  legs  were  of  human  proportions,  he 
would  stand  over  seven  feet  high.  His  hands  and  feet  are 
almost  man's.  His  courage  is  unbounded,  his  strength  pro- 
digious. His  humanoid  skull  has  retreated  behind  enormous 
jaws  and  beneath  powerful  ridges  required  to  support  the 
muscles  to  work  the  jaws.  He  is  the  blackest  Anthropoid ;  his 
skin  is  nearly  black;  his  hair  is  coarse  dark  brown,  whitening 
with  age. 

The  chimpanzee,  like  the  gorilla,  lives  in  jungle  Africa. 
Like  the  gorilla,  he  has  a  shuffle-along  gait,  swinging  his 
body  between  his  long  crutch-like  arms.  He  has  the  gorilla's 
proportions,  but  never  the  great  bulk  of  chest.  And  so  is 
more  at  home  in  the  trees,  where  he  builds  his  nest,  as  does 
the  orang.  The  chimpanzee's  skull  is  not  unlike  the  one  ape- 
man  erect  tried  on  when  turning  into  man — and  gave  up 
because  it  had  too  much  jaw  for  the  teeth  required  and  not 
enough  brain-box  for  ideas. 

Our  other  two  cousins  are  Asiatics.  The  larger  is  that  red- 
headed satire  on  the  human  race,  the  Wild  Man  of  Borneo 
and  Sumatra;  known  to  the  natives  as  orang-utan,  to  science 
as  Simia  satyrus.  The  orang  is  the  original  roundhead.  He 
is  chunky,  rather  lazy,  but  has  a  good  mind.  He  moves  into 
a  new  nest  when  he  has  eaten  up  all  the  figs  and  young  leaves 
in  the  neighborhood  of  the  old  one.  With  his  four-foot  body 
and  his  seven-and-a-half -foot  arm-spread,  he  can  swing 



through  the  forest  faster  than  a  man  can  run.  He  slows  up 
on  the  ground,  where  he  is  less  at  home. 

The  gibbon  (Hylobates)  is  the  prima  donna  of  the  Anthro- 
poids. If  our  weightiest  opera  star  could  sing  as  loud  in 
proportion  to  size  of  body  as  can  the  slender  three-foot-high 
gibbon,  she  could  drown  the  siren  of  the  Leviathan. 

There  are  several  varieties  of  gibbon,  marked  chiefly  by 
hair  and  skin  color.  None  is  so  dark  as  the  African  apes. 
With  arms  relatively  longer  even  than  the  orang's,  they  swing 
across  the  forests  of  south-eastern  Asia  with  amazing  skill  and 
rapidity.  For  hours  on  end  they  clear  fifteen-foot  spaces; 
as  much  as  forty  feet  when  in  a  hurry. 

In  shape  of  skull  and  character  of  teeth  the  gibbon  is  the 
most  primitive  ape,  and  thereby  the  most  humanoid  and 
nearest  the  source  of  man's  origin.  He  walks  erect,  his 
arms  are  free  and  straight,  his  brain-centers  for  touch  and 
hearing  are  humanoid.  In  other  words,  of  our  four  first 
cousins  the  gibbon  has  the  closest  speaking  likeness  to  our 
great-grandf  ather. 

The  Cercopithecidae  share  with  man  and  man-like  apes  the 
doubtful  honor  of  having  thirty-two  teeth,  a  narrow  nose,  a 
tail  more  ornamental  than  useful,  and  a  thumb  which  can 
describe  a  circle.  Their  big  toe  is  equally  opposable,  a 
trait  we  generally  leave  in  the  cradle.  They  have  no  vermi- 
form appendix;  as  compensation,  they  have  callused  rumps. 
These,  in  mandrills,  together  with  the  cheeks,  are  gorgeously 
colored;  rarely  are  more  brilliant  blues,  lilacs,  and  scarlets 
found  in  nature. 

The  baboon  is  named  Cynocephalus  from  his  dog-like  head. 
He  walks  on  all-fours,  has  long  since  abandoned  tree  life, 
and  is  so  strong  and  savage  that  he  easily  holds  his  own  on 
the  ground.  He  has  the  meanest  disposition,  and,  in  spite  of 
fine  fur,  painted  cheeks,  and  brilliant  bottom,  is  the  least 
prepossessing  of  the  Primates. 

The  macaques,  of  which  the  Barbary  ape  of  Gibraltar  is 
the  only  Primate  but  man  living  in  Europe  in  historic  times, 



are  mostly  Asiatic.  One  species  lived  in  Japan,  and  is 
preserved  in  inimitable  art.  In  fact,  never  did  contact  be- 
tween two  First  Families  lead  to  such  happy  results  as  when 
they  posed  for  Japanese  artists. 

The  two  American  First  Families  (2  and  3)  are  just 
monkeys.  They  have  broad  flat  noses,  no  cheek  pouches  or 
callused  rumps,  tails  generally  prehensile,  and  a  thumb  often 
tiny  and  never  opposable. 

The  tiny  marmosets  are  greatly  prized  by  sailors,  and,  since 
the  opening  of  the  Panama  Canal,  many  spend  their  last 
days  aboard  a  warship.  They  have  the  same  number  of 
teeth  a  sailor  ought  to  have. 

The  Cebidae  include  all  other  New  World  monkeys.  They 
have  thirty-six  teeth,  humanoid  nails — flat,  instead  of  claws — 
and  a  tail  as  good  as  a  fifth  hand.  The  best  known  Cebida 
is  the  capuchin,  named  from  its  monkish  garb — often  dis- 
guised by  the  rags  of  his  bondage  to  an  Italian  organ-grinder. 
This  contact  between  First  Families  may  please  the  children, 
but  has  not  led  to  art.  Probably  a  capuchin  is  no  happier 
on  the  East  Side  than  is  a  marmoset  on  a  flagship.  Yet  the 
tiny  marmoset  has  the  brain  of  man  at  the  third  month  of 
fetal  life. 

The  lemurs  are  our  poorest  relations — poorest  in  all  that 
makes  for  kinship  between  man  and  monkey.  They  live  in 
the  trees,  prowl  around  all  night,  sleep  all  day.  Their  body 
resembles  that  of  a  four-footed  animal.  Their  brain  also 
is  of  low  type;  the  hemispheres  of  the  fore  brain  are  small 
and  do  not  cover  the  hind  brain.  Their  second  toe  is  a  claw, 
often  weirdly  long. 

It  is  a  far  cry  from  man  to  lemurs,  but  the  links  yet 
missing  are  not  between  man  and  the  great  apes,  but  between 
the  great  apes  and  the  gibbon  and  between  the  gibbon  and 
monkeys.  In  one  sense  the  great  apes  are  halfway  between 
man  and  gibbon,  yet  the  gibbon  is  much  closer  to  the  three 
than  to  monkeys.  It  is  also  related  in  many  ways  to  the 
New  World  monkeys.    Hence  it  is  likely  that  gibbon.  Old 



World  monkeys,  and  New  World  monkeys  all  came  from  a 
common  stock.  The  New  World  monkeys  developed  in  one 
direction,  the  Old  World  monkeys  in  another.  But  while 
the  gibbon  preserved  and  perfected  its  purely  arboreal 
mechanism,  it  also  developed  an  upright  posture  and,  when 
on  the  ground,  an  upright  gait.  Orang,  chimpanzee,  and 
gorilla  also  specialized,  each  in  its  own  way.  The  gorilla 
evolved  the  largest  brain,  but  only  larger  than  chimpanzee's 
as  its  body  is  larger. 

The  gibbon,  in  common  with  the  great  apes,  can  be  inocu- 
lated with  infectious  diseases:  syphilis,  for  example.  Such 
inoculation  in  monkeys  leads  only  to  slight  disturbance. 
Monkeys  do  not  respond  to  the  test  for  human  blood,  nor 
do  any  other  mammals  except  the  four  Anthropoids. 

The  common  ancestral  stock  of  man  and  Anthropoids  de- 
veloped in  two  directions:  the  gibbon  remained  small;  the 
others  became  heavy  and  partly  took  to  the  earth.  Man 
came  from  that  group  and  left  the  trees  altogether.  But 
even  as  he  turned  in  our  direction,  his  equipment  was  in- 
valuable. His  long  sojourn  in  the  tree-tops  and  his  agility 
in  swinging  through  the  forest  were  a  great  education,  for, 
as  Lull  says,  "every  hand-leap  required  that  he  instantly 
solve  a  compound  problem  in  mathematics  made  up  of  dis- 
tance, trajectory,  direction,  and  strength  of  limb."  When 
he  did  not  solve  that  problem,  he  crashed!  Mental  prepared- 
ness had  a  high  premium  in  those  days. 

We  often  wonder  where  we  get  our  brain;  it  was  stand- 
ardized a  million  years  ago.  From  stock  such  as  the  gibbon, 
man  also  sprang.  That  life  in  the  trees  gave  him  his  start 
toward  his  big  brain.  There  was  no  "fall";  man  climbed 
down.    And  that  is  a  story  of  changing  limbs. 


There  is  nothing  in  man's  arm,  from  the  muscles  by  which 
it  is  fastened  to  his  head,  neck,  and  spine,  to  his  finger  nails, 



that  does  not  show  modification  due  to  change  in  function 
since  man  left  the  trees.  The  gibbon  line  started  the  changes. 
He  can  stand  as  straight  as  man;  his  shoulders  have  already 
swung  around  to  the  side  of  his  body,  his  thorax  begins  to 
assume  the  human  type. 

Our  ancestor  needed  a  long  forearm  and  a  short  upper 
arm.  In  swinging  through  the  trees  the  body,  attached  to 
the  lever  at  the  shoulder,  is  the  weight;  the  fulcrum  is  in  the 
elbow;  the  biceps  muscle  furnishes  the  power  to  the  moving 
lever  or  upper  arm.  The  greater  the  distance  of  this  lever 
from  the  fulcrum,  the  greater  the  power.  The  biceps  muscle 
in  the  gibbon  has  extra  heads  of  insertion,  the  better  to  lift  the 
greater  weight. 

Our  ancestral  arm  became  modified  to  meet  a  change  in  oc- 
cupation. With  hand  work,  the  movable  lever  was  no  longer 
the  upper  but  the  forearm.  Men  vary  greatly  in  relative 
length  of  upper  to  forearm,  but  in  general  our  forearm  is 
short  and  powerful.  We  do  not  need  the  extra  heads  of  inser- 
tion for  our  biceps,  but  one  man  in  ten  still  has  them. 

Why  did  not  man  fly  down?  That  would  have  been 
speedier.  In  a  pinch  he  could  fly  up  again.  To  fly  is  to  be 
free.  Bats  can  fly.  They  are  high  mammals;  they  are  marvel- 
ously  free.  But  at  what  a  price!  They  lost  their  hands.  They 
cannot  handle  things.  A  baby  can;  does.  That  handling  of 
things  is  a  priceless  possession,  worth  more  than  eagle's 
wings.  With  hands  the  baby  brings  things  up  to  its  eyes, 
ears,  nose,  mouth;  turns  things  over,  examines  them  from 
all  sides;  prods  things  to  see  if  they  are  alive;  shakes  them 
to  learn  if  they  are  hollow;  feels  them  to  find  out  if  they 
are  ripe  or  rotten  or  hard  or  smooth  or  hot;  feels  its  own 
body,  explores  itself. 

The  monkey  is  no  less  handy,  rather  more  so;  and  mar- 
velously  quick.  The  hand  of  a  baboon  in  a  Calcutta  zoo  shot 
over  a  high  wire  screen  and  picked  my  spectacles  from  my 
eyes ;  I  knew  he  had  them  only  when  I  saw  them  in  his  hands. 
He  twisted  the  wires  into  a  shapeless  mess  and  broke  the 



lenses  into  tiny  bits;  nor  gave  me  revenge  by  cutting  his 

It  is  enormously  significant  that  a  normal  newborn  can 
hang  by  its  hands  for  half  a  minute;  three  weeks  later,  for 
two  or  possibly  three  minutes.  Not  so  much?  Try  it.  An 
average  three-weeks-old  baby  can  outhang  an  average  thirty- 
year-old  parent.  It  is  a  doting  father  that  encourages  baby 
to  get  its  fingers  in  his  beard;  it  "hangs  on  for  dear  life." 
So  it  does.  It  had  to,  once,  or  fall.  That  was  the  way  it 
clung  to  home  and  mother  up  a  tree. 

Primitive  peoples  to-day  walk  up  and  down  trees,  "like 
a  monkey."  Some  tribes  make  their  homes  in  trees.  Arm- 
less men  can  learn  to  write  and  shave  with  their  toes. 

When  a  boy  drops  from  a  limb,  his  legs  bend  out  at  the 
knee  and  hip  joints.  When  he  falls,  he  generally  breaks 
something.  The  legs  and  feet  of  a  newborn  babe  are  no 
good  at  all  for  walking  on  a  flat  surface.  The  legs  are 
crooked,  the  feet  turn  in.  When  it  can  walk,  it  does  not 
walk  on  the  soles  of  its  feet,  but  on  the  outer  rim  of  the 
soles.  The  bones  under  that  outer  rim  are  the  first  to  appear 
in  fetal  life.  The  baby  can  wriggle  its  big  toe  almost  as 
much  as  its  thumb.  Its  drawn-up  crooked  leg,  inturned  foot, 
and  opposable  toe  are  lingering  mementoes  of  the  days  when 
our  feet  were  more  at  home  on  the  limb  of  a  tree  than  on 
the  ground.  Our  hand  is  very  wonderful,  but  not  so  "human" 
as  our  foot. 

Even  our  ancestral  backbone  was  almost  human.  It  was 
not  arched,  as  is  the  dog's;  it  was  already  a  column.  Not 
for  months  can  the  baby  stand  up,  but  it  can  soon  sit  up. 
Man  sat  up  on  a  limb  before  he  stood  up  on  the  earth.  If  we 
must  "point  with  pride"  to  some  part  of  our  anatomy  denied 
our  monkey  ancestor,  it  is  not  to  our  spine  or  to  our  hand,  but 
to  our  foot.  To  become  human,  the  foot  had  to  travel  as 
far  as  our  brain.  Yet  we  hide  it  in  a  shoe  made  on  the 
toe  formula  of  a  spider  monkey.  Our  longest  toe  is  our 
big  toe;  if  not,  our  foot  is  a  throw-back  and  a  poor  relation. 



The  human  foot  at  best  is  a  misfit  and  is  not  improved  by 
being  shod.  By  the  time  we  have  lost  our  lower  jaw  through 
disuse,  we  shall  have  lost  all  our  toes  but  the  big  one.  Our 
foot  will  then  be  as  highly  specialized  as  a  horse's.  Of  all  the 
Primates,  man's  foot  is  the  most  primitive;  next  is  the  go- 
rilla's. Even  Pithecanthropus  is  allowed  a  human  foot  be- 
cause his  thigh  bone  was  so  human.  He  walked  like  a  man 
— and  as  man  cannot  at  birth. 

The  great  apes'  babies  also  have  short  and  crooked  legs, 
and,  like  man  babies,  but  unlike  monkey  babies,  cannot 
hang  on  to  their  mothers  by  their  fingers  and  toes.  Their 
fingers  are  only  fair  graspers  and  their  toes  worse;  their 
mothers'  bodies  have  not  enough  hair  to  hang  on  to.  They 
must  be  carried.  On  that  fact  rests  the  foundation  of  every 
human  home.  The  first  kindergarten  of  human  conduct  was 
in  the  trees. 

A  monkey  baby  clings  to  the  hair  of  its  mother's  body  by 
its  fingers  and  toes.  Lemur  babies  wrap  their  legs  around 
their  mother's  body,  cling  with  their  arms,  and  anchor  them- 
selves by  holding  on  with  their  mouth  to  one  of  the  two  extra 
teats  in  her  loins. 

Our  ancestor  neither  fell  nor  dropped  from  the  ancestral 
tree.  He  walked  down;  his  brain  had  become  too  big  for 
foliage.  It  was  the  most  important  step  in  the  life  of  the 
human  race.  His  debut  as  a  terrestrial  mammal,  with  noth- 
ing but  his  wits  as  his  principal  weapon,  was  the  culminating 
episode  in  the  drama  of  life  on  this  planet.  It  was  ages  be- 
fore he  became  a  good  actor,  but  without  his  schooling  in 
the  trees  he  could  hardly  have  become  human  in  a  million 


Man  lost  his  tail  and  began  to  acquire  his  present  stature 
and  upright  gait,  including  a  tendency  to  hernia,  during  an 



arboreal  existence  in  the  Miocene  epoch  of  the  Tertiary  era 
from  two  to  three  million  years  ago.  During  the  last  million 
years  there  has  been  little  change  in  his  stature  or  size  of 
body.  In  weight  and  length  of  trunk  and  head,  the  chim- 
panzee is  as  human  as  we  are.  The  greatest  change  was 
in  larger  head,  shorter  jaws,  shorter  body  and  arms,  longer 

During  the  Miocene,  New  World  monkeys  became  differ- 
entiated from  lemurs  and  from  the  tailed  monkeys  of  the 
Old  World.  Small  tailless  apes  not  unlike  the  gibbon  had 
evolved  from  the  Old  World  monkeys.  This  was  a  big  step 
in  man's  journey  up  off  his  belly.  Through  the  ancestor  of 
modern  gibbons,  man  lost  his  tail  and  gained  his  gait. 

Dryopithecus,  first  of  the  big-bodied  apes  which  eventually 
led  to  man,  also  appeared  during  the  Miocene.  He  is  a  pre- 
Homo.  His  line  is  quite  as  important  as  that  of  Charlemagne 
or  the  Mayflower.  It  divided.  One  branch  is  represented 
by  the  extinct  Paleopithecus  of  India  and  the  modern  great 
apes.  The  other  branch  took  to  the  earth;  from  it  came 
Pithecanthropus,  Piltdown,  and  Heidelberg  man.  But  a  mil- 
lion years  elapsed  before  any  ape  became  so  human  that  he 
could  only  be  Homo. 

Was  it  speech  that  made  man?  Speech  often  leads  to  his 
downfall,  and  in  all  the  world  is  no  mechanism  so  delicately 
poised  as  a  woman's  tongue.  But  vocal  cords  are  as  old  as 
frogs;  and  few  of  us  can  chatter  like  a  magpie  or  a  monkey. 
Nor  can  we  howl  like  a  howler-monkey  or  scream  like  a 
gibbon.  Fossil  men  left  no  voices,  nor  anything  to  suggest 
the  nature  of  their  larynx.  Yet  it  is  significant  that  the 
normal  human  larynx  has  no  such  laryngeal  pouch  reso- 
nators as  have  many  Primates.  Man  has  had  to  make  an 
amplifier.  But  no  ape  has  developed  speech  into  such  a 
perfect  medium  of  communication  as  man.  This  is  not 
alone  due  to  any  imperfection  in  voice  mechanism. 

Was  man's  appearance  due  to  his  big  brain?    The  brain 



weight  of  a  tuna  fish  compared  to  its  body  weight  is  as  1  to 
37,000;  of  an  ostrich,  1  to  1,200;  of  a  horse,  1  to  500;  of  a 
frog,  1  to  170;  of  a  gorilla,  1  to  120;  of  a  lemur,  1  to  40;  of 
man,  1  to  35.  But  brain  weight  to  body  weight  in  rat  and 
magpie  is  as  1  to  28;  in  marmoset,  1  to  22;  in  capuchin,  1 
to  13.  The  place  of  honor  goes  to  the  humming-bird,  1  to  12. 

Imagine  a  human  being  with  a  brain  as  large  in  proportion 
to  his  body  as  has  a  humming-bird! 

But  in  weight  of  brain  in  proportion  to  weight  of  spinal 
cord,  man  exceeds  all  creation:  50  to  1;  in  the  gorilla,  it  is 
20  to  1;  in  mammals  below  Primates,  5  to  1;  in  birds,  be- 
tween 10  and  2  to  1;  in  fishes,  1  to  1.  Spinal  cord  is  good, 
but  brains  are  brains.  And  there  is  nothing  in  the  world 
like  them. 

Longevity  among  Primates  began  with  the  great  apes.  If 
adolescence  ends  with  a  full  set  of  teeth,  adult  life  in  man 
begins  at  twenty-two,  in  the  great  apes  at  fourteen.  Keith 
holds  that  man's  age  at  sixty-six  is  equivalent  to  that  of  the 
gibbon  at  eighteen,  of  the  great  apes  at  forty-two;  and  that 
a  native  Australian  of  forty-two  shows  the  age  changes  of 
a  European  of  sixty-two. 

There  are  no  marked  sexual  differences  among  gibbons; 
as  a  rule,  the  female  is  a  bit  heavier.  In  the  chimpanzee, 
sexual  differences  are  about  the  same  as  in  man.  Orangs 
and  gorillas  show  marked  differences,  the  gorilla  especially. 
The  male  is  larger,  heavier,  stronger;  his  jaws  and  teeth,  es- 
pecially the  canines,  are  more  powerful.    He  is  the  fighter. 

Secondary  sexual  characters  in  man  thus  appear  to  be 
only  one  or  two  million  years  old.  They  seem  to  be  dimin- 
ishing. Nature  gets  rid  of  useless  structures  or  finds  new 
functions  for  them.  Modern  woman  shows  no  great  disposi- 
tion to  find  any  new  function  for  them. 

Europe  or  Asia?  Hrdlicka  says  Europe — through  Pilt- 
down  man  to  Dryopithecus,  the  Miocene  ape.  Osborn  says 
Asia:  "Asia  is  near  a  center  of  evolution  of  a  higher  Primate; 
there  we  may  look  for  the  ancestors  not  only  of  prehuman 



stages  like  the  Pithecanthropus,  but  of  higher  and  truly- 
human  types." 

In  that  case,  prehistoric  man  in  Europe  was  an  immigrant 
from  Asia,  as  was  prehistoric  man  in  America.  Possibly 
Asia,  in  a  not  too  remote  age,  will  lead  the  race  to  be  more 




1.  Life's  Genealogic  Time-table.  2.  The  Hand  That  Rocks  the  Cradle. 
3.  Experiments  in  Brains.  4.  New  Styles  in  Eggs  and  Incubators.  5.  Our 
Indebtedness  to  Fish.  6.  Back  to  the  Lifeless  Earth.  7.  The  Start  from  the 
Sun.  8.  The  L  M  N's  of  Nature.  9.  The  Fitness  of  Water  and  Carbon 
Dioxide.  10.  The  Evolution  of  the  Organic.  11.  Darwin  and  Natural 
Selection.  12.  Lamarck  and  Acquired  Characters.  13.  The  Nature  and 
Evolution  of  Sex.  14.  The  Colored  Bodies  of  the  Egg.  15.  The  Great  Game 
of  Heredity.    16.  Eugenics,  or  Being  Well  Bred. 


The  race  to  be  human  began  with  the  first  living  being. 
That  being  was  possible  because  the  earth  brought  from  the 
sun  some  very  remarkable  elements  and  because  the  sun 
continued  to  shine.  Under  its  beneficent  rays,  certain  ele- 
ments became  so  dynamically  constituted  that  they  began  to 
perform  like  an  organic  individual.  It  could  do  what  matter 
had  not  done  before,  behave  like  a  living  being.  It  grew, 
but  its  size  was  limited  by  its  nature,  as  is  that  of  a  raindrop 
or  a  drop  of  oil  or  a  piece  of  jelly.  It  split  up.  It  developed 
new  ways  of  growth,  and  evolved  sex.  Various  theories  have 
been  proposed  as  to  how  all  this  came  about;  even  propa- 
ganda for  taking  the  future  of  the  race  in  our  own  hands. 
These  are  to  be  our  concern  in  this  chapter.  A  time-table 
of  life  will  start  us  off".  With  that  before  us,  we  can  soon 
trace  our  body  back  to  a  bacterium  or  something  just  as 
good.  It  is  a  long  journey,  but  we  shall  try  to  keep  out  of 
blind  alleys  from  which  there  is  no  return.  Meanwhile,  do 
not  forget  that  the  egg  with  which  we  begin  life  has  been 
living  since  life  began;  that  egg  has  had  a  long  history  and 



(Modified  from  Organic  Evolution,  by  Richard  Swan  Lull,  1921, 
by  permission  of  the  author  and  the  pubhshers,  The  Macmillan 


Ennph  or 

x-jyjyjyji-i.  yji. 




Age  of  Man 




Age  of 

(Ice  Age) 

End  of  great  mammals 




Man-ape  became  Man 


Culmination  of  mammals 


Higher  mammals 


End  of  archaic  mam- 

Age  of 

Archaic  mammals 




End  of  great  reptiles 





Age  of 
r  isnes 

y^aX  JJUllllcl 


End  of  ancient  life 



Land  vertebrates 

Primitive  reptiles 

Ancient  sharks 




Lung  fishes 


Armored  fishes 




First  invertebrates 




Unicellular  life 



has  learned  much  about  life.  Otherwise  we  could  not  learn 
to  behave  like  human  beings  in  so  short  a  time. 

Our  most  human  parts — brain,  skull,  teeth,  voice  organs, 
upright  gait,  and  fingers — are  not  new,  they  are  not  unique, 
they  are  not  ours  exclusively;  for  life  itself  they  are  not 
even  essential.  Some  human  beings  never  use  their  brains, 
their  skull  is  merely  a  frame  for  features,  they  lose  all  their 
teeth,  and  their  fingers  are  all  thumbs.  No,  our  most  human- 
oid  parts  will  not  give  us  much  clue  to  the  nature  of  the 
ceaselessly  changing  creature  that  became  at  last  human. 

A  man,  monkey,  opossum,  lizard,  frog,  shark,  flea,  fish- 
worm,  oyster,  and  malaria  germ  have  one  thing  in  common: 
they  must  eat  and  breathe,  or  die.  Every  animal  must  have 
lungs  and  stomach,  or  the  equivalent.  Call  it  viscera.  Viscera 
are  vitals,  the  something  without  which  there  is  no  living 
animal.  What  else  have  they  in  common?  A  motor  mechan- 
ism to  bring  the  necessary  elements  of  life  within  reach  of 
the  living  body's  vitals. 

The  great  difference  between  man  and  oyster  is  not  viscera, 
but  motor  mechanism.  That  difference  is  so  great  that  man 
can  catch  the  oyster  and  eat  it.  The  most  the  oyster  could 
catch  of  man  is  a  finger,  and  then  only  if  man  carries  his 
finger  to  the  oyster  and  invites  the  oyster  to  catch  it.  Even 
then  the  oyster  could  not  eat  the  finger.  The  motor  mechan- 
ism of  man  and  higher  animals  is  knit  together  by  a  nervous 
system,  supplemented  by  vocal  organs  and  presided  over  by 
a  brain. 

The  history  of  our  body  is  primarily  that  of  the  mechanism 
for  getting  food,  ways  of  avoiding  being  eaten  as  food,  and 
method  of  growth.  In  other  words,  the  chemical  activities 
whereby  living  beings  maintain  life  are  fundamentally  the 
same  in  all  animals,  but  the  laboratory  in  which  these  activ- 
ities take  place  and  the  mechanisms  for  carrying  the  labora- 
tory about  and  for  acquiring  information  as  to  food,  enemies, 
etc.,  vary  enormously. 

Even  our  Primate  ancestor  up  a  tree  lacked  no  parts  to 



become  human;  certain  parts  merely  had  to  be  altered.  Say, 
two  million  years.  Beyond  these  two,  other  millions  passed 
while  body  and  brain  bided  their  time;  the  earth  was  not 
yet  quite  ready  for  nature's  great  experiment. 

As  Bergson  puts  it:  "Man  only  realized  himself  by  aban- 
doning a  part  of  himself  on  the  way;  he  was  not  yet  ready 
to  fight  for  his  life  with  his  mere  wits."  Wits  are  his  greatest 

We  must  not  think  of  our  body  as  the  most  or  the  best  this 
or  that.  In  many  ways  the  eagle  has  a  more  specialized  struc- 
ture; it  excels  in  eyesight,  respiratory  system,  skeleton,  and 
locomotion.  Even  the  bee  in  its  own  line,  as  Thomson  says, 
is  hardly  inferior  to  man  and  represents  an  achievement  that 
angels  might  desire  to  look  into. 

Life  has  tried  out  countless  bodies.  Certain  species  of 
snails  and  Crustacea  have  survived  almost  unchanged  from 
pre-Cambrian  days,  sixty  million  years  ago.  Two-million- 
year-old  fossil  ants  embalmed  in  amber  are  so  much  like 
ants  of  to-day  that,  could  they  awake  from  their  sleep,  they 
could  recognize  their  descendants,  if  their  noses  were  not 
stopped  up.  They  kept  to  the  middle  of  the  road.  That 
man  evolved  from  a  lowly  Primate  means  that  the  Primate 
itself  was  neither  an  accident  nor  a  highbrow,  that  it  was 
not  too  far  removed  from  the  body  its  ancestor  brought  up 
out  of  the  mud  on  to  the  dry  land. 

Many  families  of  Nature's  masterpieces  have  no  living 
representative  because  they  over-specialized;  they  gave  up 
so  much  to  tusk,  trunk,  canine,  wing,  leg,  stomach,  size, 
height,  length,  or  armor,  that  they  had  not  enough  to  live 
on.  They  put  all  their  eggs  in  one  basket.  Earth's  crust 
is  full  of  these  fancy  forms,  so  specialized  they  could  not 
meet  change.  Man  got  ahead  because  he  could  grasp  an 
idea,  could  talk  it  over  with  his  fellow-men  and  think  up 
new  ideas.  The  amazing  thing  is  not  that  he  became  human, 
but  that  he  can  be  so  inhuman  in  so  many  ways. 

The  fundamentals  of  living  remained  unchanged  through 



vast  periods  of  time,  the  structure  in  which  vital  processes 
functioned  kept  changing.  When  the  larder  shifted  or  the 
nature  of  its  contents  changed,  the  method  of  keeping  the 
viscera  in  touch  with  the  larder,  or  in  preparing  food  so  that 
the  viscera  could  digest  it,  had  to  change.  Countless  animals 
still  solve  the  problems  of  life  with  simple  structures.  Few 
went  in  for  brains.  None  but  man  ever  tried  to  discover  the 
nature  of  brains  or  thought  of  preserving  them  in  alcohol. 
He  could  do  this  because  the  body  he  inherited  could  be 
adapted  to  diverse  occupations. 

Reading  the  time-table  backward  suggests  a  parallel  proc- 
ess which  seems  to  have  been  at  work  in  human  culture: 
progress  by  leaps;  between,  long  pauses.  The  pauses  grow 
shorter  as  time  moves  on. 

For  a  hundred  thousand  years  man  gets  along  without 
steam-control.  The  steam  engine  is  invented.  In  the  twink- 
ling of  an  eye  steamships  plow  the  seas  and  every  land  is 
ribbed  with  shining  rails.  The  Age  of  Steam  blossomed 
out  of  nothing.  Gossip  formerly  passed  from  mouth  to  ear; 
at  breakfast,  now.  Cape  Town  reads  of  the  color  of  the  hair 
of  the  girl  the  Prince  of  Wales  danced  with  the  night  before 
on  Long  Island.   This  is  another  New  Age. 

How  did  man  get  along  without  radio,  newspaper,  steel, 
steam,  plumbing,  arch,  calendar,  spear,  flint  knife,  fire?  He 
did.  But  he  gets  along  faster  with  them.  So  with  life  itself. 
It  got  along  without  mammary  glands  and  internal  incubators, 
skull  and  vertebral  column,  head  and  tail,  brains.  But  with 
brains,  head,  backbone,  and  placenta,  the  procession  speeded 
up,  life  shot  out  in  new  directions. 

Progress  is  often  made  by  lying  low;  let  the  other  fellow 
try  out  Nature's  new-fangled  notions.  By  holding  out,  man 
came  on  the  stage  during  the  big  scene.  When  the  call  went 
forth  for  clever  people  who  could  double,  shifty  people  who 
could  walk  back  to  town  if  the  show  "blew,"  who  could  catch 
and  fry  their  own  fish  in  case  of  need,  who  could  dig  out, 
swim  across,  climb  up  and  jump  down,  who  were  handy 



with  their  hands,  had  good  memories  and  could  mix,  man 

All  this  took  brains:  a  big  brain,  a  brain  so  big  it  had  to 
wrinkle  or  burst  its  case;  a  brain  with  frontal  lobes  so  big 
they  dwarf  the  hind-brain.  A  brain  big  in  every  way;  in 
absolute  size  and  weight,  in  proportion  to  spinal  cord,  in 
proportion  to  body. 

Think  of  a  jellyfish,  a  shark,  or  an  elephant  with  a  human 
brain.  The  jellyfish  has  no  head  to  put  it  in;  the  shark,  no 
bony  skull  to  protect  it;  the  elephant,  no  hands  to  do  its 
bidding.  The  human  brain  would  be  an  incumbrance  to  the 
jellyfish,  a  nuisance  to  the  shark,  and  would  drive  the  elephant 

Nature  has  made  many  extraordinary  experiments.  Some 
survive:  their  parts  had  "survival"  value;  most  of  them  dis- 
appeared. But  no  great  group-experiment  was  a  total  failure. 
Even  the  Cyclops-eyed  reptile  of  pre-Tertiary  times  survives 
in  the  Sphenodon  of  New  Zealand.  The  eye  itself,  as  eye, 
was  a  failure;  we  inherit  it  as  endocrine  gland! 


If  the  hand  that  rocks  the  cradle  is  the  hand  that  rules  the 
world,  it  will  not  hurt  good  government  if  the  hand  knows 
what  it  rocks;  or  what  the  hand  came  from;  or  that  the  first 
cradle  was  in  a  tree-top.  The  human  brain  and  throat  made 
civilization  possible,  but  it  was  the  hand  that  built  the  home, 
kindled  the  fire,  and  made  human  culture.  There  are  simpler 
and  surer  feet  than  man's,  but  none  has  carried  such  price- 
less freight  or  been  shod  with  the  wings  of  a  Perseus.  The 
human  hand  should  build  a  monument  to  the  human  foot,  for 
the  foot  freed  the  hand! 

In  a  class  on  Christian  Evidences,  the  President  of  the 
college  wiggled  his  thumb  and  said,  triumphantly,  "No 
monkey  ever  lived  that  could  do  that!"  Could  if  it  wanted 
to.  Watch  a  monkey  climb  a  rope :  thumb  on  one  side,  fingers 



on  the  other.  Sally,  the  chimpanzee,  grasps  the  neck  of  a 
bottle  like  a  man,  and  opens  a  clam  shell  with  the  thumbs  of 
her  two  hands.  Watch  a  monkey  on  a  still  hunt  through  the 
hair  of  its  mate. 

Opposability  of  thumb  is  no  marvel.  The  marvel  is  that 
an  organ  modified  for  grasping  limbs  can  also  pick  up  a 
pin,  throw  a  stone,  wring  a  chicken's  neck,  and  crack  a  nut 
with  a  rock.  Any  average  monkey  has  a  pair  of  such  marvels. 
The  fact  is  that  if  a  primitive  five-toed  foot  had  not  been 
carried  into  a  tree  and  there  developed  along  lines  of  its 
original  pattern,  there  would  be  no  human  hand  to  grasp 
to-day.  It  was  figuratively  and  literally  kept  in  the  air. 
Had  it  specialized  either  as  grasper  or  as  support,  it  could 
not  have  been  turned  into  the  marvelous  organ  that  it  is. 

The  monkey  was  not  the  only  mammal  that  took  to  trees; 
the  whole  marsupial  family  started  their  career  there.  The 
kangaroo  came  down;  his  prehensile  forefoot  lost  its  offset 
great  toe.  The  koala  remained;  his  forefoot  developed  an 
opposable  thumb  and  an  opposable  first  finger.  No  vine  is 
a  better  dinger.  When  you  shoot  a  koala  you  climb  the 
tree  and  pry  its  fingers  loose  or  it  will  hang  there  till  it  rots. 
Tree-sloths  (cousins  to  armadillos)  also  specialized  in  grasp- 
ing organs.  One  has  only  three  fingers,  each  armed  witli 
hook-like  claws;  its  hooks  also  hang  on  after  death.  Our 
ancestors  were  adapted  to  an  arboreal  life;  they  were  not 
enslaved  by  it. 

Some  Primates  experimented  in  fingers.  A  lemur  lost 
his  second  finger  to  give  the  thumb  more  grasping  space. 
Some  tried  claws  instead  of  nails.  The  marmoset  has  a 
thumb  nail,  the  other  fingers  have  curved,  pointed  claws.  As 
Primates  progressed,  nails  replaced  claws  and  all  five  fingers 
were  put  to  use.  With  the  gibbon,  the  prehensile  hand  was 
well  developed.  Early  lemurs  lived  on  rather  than  in  the 
tree-tops.  The  gibbon  does  not  walk  on  trees,  but  swings 
from  limb  to  limb.    Its  hand  is  more  specialized  than  ours, 



farther  evolved  from  the  ancestral  type.  The  orang's  thumb 
is  almost  gone;  often  has  no  nail. 

Several  animals  tried  out  the  prehensile  tail:  chameleons, 
opossums,  an  ant-eater,  and  some  New  World  monkeys.  Old 
World  monkeys  were  wiser.  The  spider  monkey's  marvelous 
tail  cost  him  two  thumbs;  in  gaining  a  "fifth  hand"  his  true 
hands  lost  their  perfection. 

Invertebrates  are  allowed  as  many  legs  as  they  please  up 
to  a  millipede.  The  vertebrate  limit  is  four,  two  pairs.  They 
began  with  fishes:  gills  modified  for  propulsion.  Their 
limbs  are  oars;  the  tail  is  rudder  and  sculling  oar.  When 
fish  crawled  out  of  the  water  on  their  belly,  their  limbs 
were  paddles — as  are  ours  in  fetal  life.  Many  vertebrates 
kept  on  crawling  on  their  bellies,  and,  like  most  snakes,  lost 
their  paddles.  Whales  went  back  to  water  and  turned  their 
front  legs  into  oars  again;  they  lost  their  hind-limbs. 

Man  never  was  a  whale  or  a  snake;  nor  did  he  ever  walk 
like  a  horse.  He  did  not  go  in  for  stability,  as  did  the  horse, 
cow,  and  elephant;  mobility  was  his  goal.  In  bones,  muscles, 
and  plan,  our  forelimb  is  closer  to  a  frog's  than  to  a  cow's. 
It  is  built  on  the  old  fish  type  handed  on  by  amphibians  to 
reptiles.  Compared  with  the  front  foot  of  a  horse,  our  hand 
is  primitive  and  ancient,  closer  to  the  hand  of  an  extinct 
iguanadon  of  Jurassic-Cretaceous  times. 

With  that  type  of  limb  the  first  Primates  climbed  a  tree. 
It  was  a  four-piece  arm:  humerus,  swinging  free  at  the  side 
and  held  against  the  shoulder-blade,  which  in  turn  was  held 
out  and  away  from  the  body  by  the  collar-bone  acting  as  a 
strut;  forearm  of  radius  and  ulna,  making  possible  the  right- 
side-up,  upside-down  hand  movements;  wrist  joint  of  eight 
bones;  five  fingers.  These  bones  can  all  be  matched  in  the 
"hand"  of  a  mud  turtle,  but  not  in  the  forefoot  of  a  horse. 
The  turtle's  wrist  has  one  more  bone,  the  central.  All  men, 
gorillas,  and  chimpanzees  have  it  in  the  fetal  hand.  It  then 
incorporates  with  the  scaphoid  bone.  It  sometimes  forgets  to 



When  our  ancestor  walked  down  the  tree,  his  f  orelimb  was 
already  an  arm  and  a  hand;  the  tree  had  saved  it  from  a 
leg's  fate.  His  hand  could  grasp  the  ball;  his  arm  could 
"wind"  it  up,  as  does  the  pitcher  before  he  puts  it  over.  It 
did  not  have  far  to  go  to  become  the  hand  that  rocks  the 

A  large  litter  is  wasted  energy  without  a  suitable  nursery. 
The  horse  specialized  in  grass-cutting  teeth  and  fast  legs. 
It  has  no  nursery;  the  colt  can  run  the  day  it  is  born.  It  must, 
or  the  wolves  will  get  it.  Our  Primate  mother  had  no 
natural  nursery,  but  she  had  a  natural  clinging  disposition — 
as  had  her  baby.  As  brain  and  body  developed,  the  baby's 
dependence  on  its  mother  became  more  profound.  Apes 
carry  their  young  in  their  arms,  as  does  man.  Even  a  young 
gibbon  is  dependent  on  its  mother  for  seven  or  eight  months; 
she  carries  it  to  the  water,  bathes  it,  dries  it.  A  gorilla 
mother  boxes  her  young  hopeful's  ears,  and  the  male  guides 
and  guards  all  his  children. 

Interpret  all  this  in  terms  of  pa,  ma,  and  the  baby.  The 
family  grows  larger.  Family  circle.  Divided  cares,  mutual 
responsibility.   Human  behavior  began  up  there. 

The  tree-living  Marsupial  carries  her  young  in  a  pouch: 
a  marvelous  contrivance,  a  wonder-work  of  nature.  The 
tree-living  Primate  carries  hers  in  her  lap.  She  had  to  sit 
up:  she  had  to  have  a  columnar  instead  of  an  arched  spine; 
hips  to  hold  viscera;  head  poised  at  one  end  of  the  spine  for 
better  control;  chest  flattened  to  agree  with  the  columnar 
spine;  diaphragm  shifted  in  position  and  moorings  to  con- 
form to  the  new  style  of  breathing;  muscles  once  needed  for 
breathing  now  used  to  hang  the  arms  at  the  sides  of  the  body 
and  swing  them  out  from  the  body. 

Such  were  some  of  the  changes  required  before  the  primi- 
tive mammal  that  climbed  the  tree  could  walk  down  and  con- 
quer the  earth.  But  not  until  earth  became  man's  home  did 
his  trunk  reach  hour-glass  form.  Then  it  was  that  the 
mammae  took  on  well-developed  nipples  and  their  encircling 



areola.  But  as  Woods  Jones  says,  something  more  subtle 
than  mere  change  in  bone  and  muscle  was  involved  in  man's 
evolution.  The  kind  of  life  lived  through  the  ages  up  the 
tree  made  possible  the  kind  of  wits  needed  to  live  at  the 
foot  of  it.  There  were  no  baby-farms  or  homes  for  children 
of  missionaries-abroad  or  officers-absent-on-foreign-duty,  in 
Miocene  times;  "mother  love"  was  more  necessary  then  for 
the  lives  of  young  apes  than  it  is  to-day  for  their  descendants. 


In  twenty  million  years  the  Age  of  Reptiles  produced  eight- 
een orders.  Five  survive;  too  much  specialization.  Osborn 
named  one  Tyrannosaurus  rex.  That  saurian  king  was  forty- 
seven  feet  long,  twenty  feet  high,  heavier  than  an  elephant. 
His  teeth  were  half  a  foot  long;  his  feet  were  armed  with 
mighty  claws.  He  was  a  perfect  machine:  in  speed,  size, 
power,  and  ferocity,  the  most  destructive  engine  that  ever 

He  is  an  also-ran.  Inside  his  thirty-six  cubic  feet  of  skull- 
box  he  had  less  than  a  pound  of  brains! 

The  big-bodied  pin-headed  Reptiles  were  gigantic  failures, 
as  were  the  first  mammals  nature  experimented  with.  Both 
turned  to  rock  and  left  no  descendants  to  mourn  their  loss. 
And  yet  they  had  had  everything  conceivable  in  dental 
weapons  and  heavy  armor.    Not  enough  brains! 

With  Oligocene  times  began  another  series  of  mammals; 
more  brains  in  proportion  to  body.  Nearly  all  of  them  are 
alive  to-day.  It  was  man's  salvation  to  have  had  a  tree- 
climbing  ancestor  at  that  time. 

Early  land  vertebrates  smelled  their  way  through  life; 
foods,  friends,  mates,  all  through  the  ends  of  their  noses. 
Like  a  dog.  The  scent  was  lost  in  the  trees;  also  the  need 
for  a  long-drawn-out  face,  like  a  horse's,  an  ant-eater's,  or 
an  elephant's.   Monkeys  do  not  touch  things  with  their  snout, 



but  with  their  finger  tips,  which  are  as  good  as  most  animals' 
tongues  for  feeling  things  out. 

Sight  is  much  more  valuable  than  smell.  Having  no  need 
for  snouts,  Primates  shortened  their  faces.  Having  little  need 
for  feet,  they  developed  their  hands.  Hands  could  bring 
things  up  to  the  eyes.  Eyes  could  settle  down  where  they 
would  be  handiest.  The  eyes  moved  on  to  the  front  of  the 
face.  Each  eye  sees  an  independent  picture,  but  the  pictures 
overlap;  the  eyes  can  correlate  and  blend  them  into  one. 
Thus,  Primates'  eyes  are  binoculars  with  stereoscopic  effect. 
Many  mammals  have  no  such  binoculars. 

What  can  an  elephant  know  of  its  body?  It  can  feel  very 
little  of  it,  see  even  less.  WTiat  does  a  monkey  not  know  of 
its  body?  What  its  hands  feel,  its  eyes  can  picture.  The 
brain  knows  nothing  of  muscles,  but  it  becomes  a  store- 
house of  pictured  movements. 

And  so  man's  headpiece  became  a  compact,  snug  affair; 
eyes,  ears,  nose,  tongue,  teeth,  all  close  together,  easily 
turned  this  way  or  that.  With  two,  sometimes  four,  hands 
available  to  bring  things  close.  The  brain  grew  as  its  re- 
quirements grew.  The  motor  mechanism  of  the  body  kept 
improving;  more  brain  needed  to  work  it.  The  more  it  was 
worked,  the  better  it  grew.  Its  areas  of  association  between 
hearing  and  seeing,  seeing  and  touching,  etc.,  kept  on  grow- 
ing. These  areas  are  the  distinguishing  features  of  man's 

If  man  had  received  no  more  than  mere  bodily  form  from 
his  monkey  ancestor,  he  might  as  well  have  had  an  opossum 
for  an  ancestor.  It  was  not  mere  body  that  made  monkeys 
smart;  nor  their  brain  that  produced  their  hand.  Their  brain 
made  the  most  of  their  hand,  but,  as  Jones  says,  while  man 
can  play  the  violin  because  he  has  a  big  brain,  what  could 
his  brain  do  if  his  hand  were  a  horse's  foot? 

Man's  ancestor  won  his  freedom  not  so  much  by  special- 
ization as  because  he  kept  his  plasticity,  extended  his  wits, 
and  improved  his  control. 




Eocene  times  knew  nothing  of  tabloid  foods  and  nature 
herself  was  the  dentist.  No  teeth,  no  food;  no  food,  no  life. 
Instead  of  a  knife,  the  primitive  Primate  used  its  incisors; 
instead  of  meat-chopper  or  mortar  and  pestle,  its  molars.  It 
stabbed  its  prey  with  its  hand,  but  kept  the  big  canine  to 
show  what  it  could  do  when  angry.  It  saved  its  teeth  by 
using  them.  They  were  not  good  for  anything  in  particular; 
they  were  good  enough  for  almost  everything  in  nature's 
larder.  Our  teeth  are  among  the  most  primitive  of  all 
mammals.  Our  four-cusped  molars  are  more  like  those  of 
extinct  Eocene  mammals  than  they  are  like  those  of  living 
apes.  We  are  the  shortest-snouted  Primate;  our  teeth,  alone 
of  Primates,  are  in  one  continuous  series.  There  is  a  real 
gap  between  canine  and  incisors  in  apes;  also  in  our  milk 
set — or  should  be,  shorter  jaws  are  lessening  the  gap. 

Our  ancestral  Primate  was  a  small,  warm-blooded,  primi- 
tive mammal  with  forty-four  teeth,  four  short  legs  all  alike, 
and  feet  with  five  toes  armed  with  claws.  It  lived  on  insects, 
worms,  fruit,  and  nuts.  \^Tio  was  its  ancestor?  How  did  it 
become  viviparous?   Where  did  it  get  its  mammae? 

Circumstantial  evidence  points  to  a  dog-toothed,  low- 
browed, Triassic  reptile,  called  Cynodont.  He  is  older  than 
the  giant  reptiles  which  appeared  millions  of  years  later, 
lower  than  the  reptiles  which  led  to  dinosaurs,  which  in 
turn  led  to  crocodiles  and  birds.  If  not  the  Cynodonts,  then 
we  must  assume  that  mammals  started  in  the  Permian  period. 
Some  say  it  w^as  in  Africa,  but  probably  Central  Asia  will 
prove  to  be  the  birthplace  of  reptiles  and  mammals. 

The  reptile  that  developed  into  mammal  had  teeth  fit  for 
a  mixed  diet.  It  could  run,  making  possible  a  broader  out- 
look and  a  surer  hold  on  life.  Legs  that  lifted  the  belly  from 
the  ground  made  warm  blood  possible.  Warm  blood  made 
energy  more  easily  available  and  personal  incubation  of  the 
egg  possible.    And  there  is  no  more  interesting  tale  in  the 



book  of  nature  than  the  one  which  recounts  her  experiments 
in  eggs. 

Mammals  get  their  name  from  their  mammae  or  milk- 
glands.  All  mammals  suckle  their  young,  although  true 
teats  appear  only  with  marsupials,  the  second  order  of 
mammals.  Monotremes,  the  lowest  mammals,  lay  eggs,  as  do 
all  birds,  amphibians,  fishes,  and  most  reptiles. 

But  there  is  a  vast  difference  between  monotreme,  bird, 
and  reptile  eggs,  and  amphibian  and  fish  eggs.  The  latter 
are  laid  in  water;  they  develop  in  water.  Amphibian  eggs 
develop  into  tadpoles  which  live  like  fish;  by  and  by  their 
gills  close,  their  tails  are  absorbed,  their  fins  become  legs; 
they  hop  up  frogs  or  toads.  But  frogs  can  no  more  live 
all  their  life  under  water  than  can  whales  or  porpoises:  they 
must  come  up  for  air.    Amphibians  lead  double  lives. 

As  do  some  men.  But  our  fetal  gill-clefts  never  break 
through.  We  can  thank  our  reptile  ancestor  for  that.  Nor 
do  reptiles  or  birds  have  gill-breathing  apparatus.  Their 
young  do  not  metamorphose  from  a  larval  stage.  The  alli- 
gator deposits  her  eggs  in  dry  ground;  if  deposited  in  water 
the  eggs  would  "drown,"  as  would  birds'  eggs. 

Reptiles,  ancestors  of  birds  and  mammals,  invented  a 
new  style  of  egg  to  get  away  from  the  double  life  led  by 
amphibians.  All  eggs  are  complex,  but  this  reptilian  egg 
was  the  first  to  have  a  shell  or  protective  envelope,  and  a 
yolk  inside:  food  to  tide  the  embryo  over  the  first  stage  of 
life,  oxygen  until  it  grows  a  lung. 

The  embryo  develops  an  amnion,  or  protective  membrane 
of  two  layers;  between,  amniotic  fluid — storm-door  and  shock- 
absorber.  Also  a  second  membrane,  the  sac-like  allantois. 
This  is  connected  with  the  embryo's  blood  vessels;  it  is  the 
embryo's  "lung."  Oxygen,  entering  through  the  pores  of 
the  eggshell,  is  picked  up  by  the  allantois  and  carried  to  the 
embryo;  the  returning  blood-stream  carries  carbon  dioxide. 
The  egg  must  have  air  or  the  embryo  within  is  asphyxiated. 



As  the  yolk-sac  diminishes,  the  allantois  grows  in  size  and 

Certain  snakes  and  all  mammals  except  monotremes  are 
viviparous:  their  young  are  born  alive.  What  has  happened? 
The  egg  is  incubated  within  the  maternal  body.  The  lung-like 
allantois  becomes  placenta  and  unbilical  cord.  The  placenta 
grows  fast  to  the  wall  of  the  mother's  uterus.  Through  the 
connecting  umbilicus  the  embryo  gets  oxygen  and  nutrition. 
Yolk — as  in  birds'  eggs — is  not  needed.  But  nature  is  per- 
sistent; the  human  embryo  has  a  yolk-sac,  but  no  yolk. 

This  vade  mecum  incubator  is  a  great  advance  over  the 
reptilian  way  of  letting  the  sun  do  it.  But  reptiles  get  the 
credit  for  the  new-style  eggs.  They  were  nature's  answer  to 
a  drought.  That  drought  gave  reptiles  their  great  start.  Those 
that  developed  blunt  dagger-like  teeth  into  grinders  with 
cusps,  and  eggs  that  could  hatch  in  a  desert,  were  the  reptiles 
that  led  to  mammals  and  man — and  made  valuable  contribu- 
tions to  science. 

Our  indebtedness  to  reptiles,  then,  is  very  great:  our  ante- 
natal robes,  four-chambered  heart,  and  a  rising  temperature 
leading  to  warm  blood.  Some  even  go  so  far  as  to  credit 
a  certain  reptile  with  our  ideas  of  the  Tree  of  Knowledge. 
Our  family  life  was  founded  in  the  trees;  but  it  is  rooted  in 
the  placenta.  The  long  and  intimate  commingling  of  parent 
and  fetus  had  far-reaching  consequences.  The  first  placenta 
was  developed  in  the  reptilian  ancestor.  By  the  time  that 
reptile  had  become  mammal,  it  had  warm  blood,  a  hairy 
body,  and  a  muscular  diaphragm  between  lungs  and  liver. 


Reptiles  developed  the  habit  of  living  on  dry  land.  An 
amphibian  pointed  the  way,  in  the  Upper  Carboniferous 
Age.  The  family  name  of  that  amphibian  is  Stegocephalia — 
because  he  had  a  roof  over  his  head.  He  may  date  from 
the  Devonian  period.    He  was  heavily  armored,  and  a  flesh- 



eater.  His  four  limbs  were  well  developed  for  crawling; 
his  bones,  in  number  and  character,  were  of  the  type  that 
millions  of  years  later  developed  into  the  prehensile  hands 
and  feet  of  Primates.  He  retained  enough  of  his  fish  habits 
to  compel  his  return  to  water  to  deposit  the  eggs.  In  the 
water  the  young  developed. 

To  that  amphibian  ancestor  we  are  indebted  for  four  price- 
less possessions:  fingers  and  toes,  true  lungs,  a  wagging 
tongue,  vocal  cords.  The  bullfrog  inherits  his  voice  direct, 
nor  is  there  evidence  that  he  has  improved  it.  It  is  known 
that  he  puts  it  to  the  use  it  had  from  the  start — a  mate-call. 
A  vocal  mate-call  could  have  been  of  no  use  under  water; 
in  swampy  lands  it  was  a  necessity. 

Beyond,  and  older  than  amphibians,  are  fishes.  Our  debt 
to  them  is  greatest  of  all:  skull,  at  first  a  rude  brain-box  of 
gristle;  true  jaws;  limbs  supported  by  bones  articulating 
with  an  axial  skeleton.  Such  parts  distinguish  us  from 
devil-fish,  oysters,  clams,  barnacles,  and  fleas.  With  such 
parts,  nature  began  to  branch  out  on  new  lines;  new  lines 
had  something  to  go  on.  They  could  develop  brain,  the 
skull  protected  it;  a  real  spinal  cord,  the  backbone  carried 
it.  With  skeleton  inside  instead  of  outside  the  body,  and  of 
bone  instead  of  shell,  they  could  develop  big  strong  bodies. 
With  their  paired  limbs  they  could  travel,  explore,  experi- 
ment. With  their  new  type  of  mental  machinery,  they  could 
record  new  experiences. 

What  an  amazing  tribute  to  the  persistence  of  nature!  Every 
normal  human  embryo  develops  a  notochord.  That  notochord 
is  the  oldest  and  only  original  "backbone,"  the  only  back- 
bone to-day  of  the  amphioxus  or  lancelet,  possibly  the  only 
living  representative  in  direct  line  of  the  inventor  of  the 
vertebrate  idea. 

From  Cambrian  days,  when  the  first  notochord  was  laid 
in  the  first  fish,  possibly  a  half -billion  years  were  to  roll 
from  the  scroll  of  life  before  man  was  to  puzzle  his  brain 
to  discover  the  nature  of  the  creature  that  decided  it  would 



be  easier  to  carry  its  skeleton  inside  its  body  than  on  its 

That  creature  is  not  yet  known.  Countless  tons  of  rock 
weigh  it  down.  It  had  no  bones,  possibly  no  shell.  Its  re- 
mains may  never  be  found;  its  soft  body  may  have  left  no 

Beyond  vertebrates,  the  skein  is  tangled.  Nature  tried 
many  types  of  bodies  before  she  found  one  fit  for  a  fish. 
That  was  no  mean  honor.  Fishes  are  highly  organized ;  they 
stand  high  in  the  tree  of  life.  The  parts  they  transmitted  to 
posterity  made  frogs,  lizards,  eagles,  monkeys,  and  man 
possible.  No  essential  part  has  been  acquired  since  the  first 
fish  laid  the  keel  on  which  every  vertebrate  builds  its  body. 
The  very  bones  of  our  middle  ear  began  their  career  in  the 
arch  of  the  gill  of  a  fish.  The  wonderful  mechanism  by 
which  we  know  when  we  are  right  side  up  was  invented  by 
a  fish. 

What  makes  a  body  fit  for  a  fish?  What  did  an  invertebrate 
have  to  have  before  it  could  think  of  becoming  a  shark  or  a 
sturgeon  or  a  cod? 

No  protozoon  would  do;  it  has  only  one  cell.  The  lowest 
multi-cellular  animals  are  sponges;  but  they  are  primitive 
and  lead  a  plant's  life.  Next  come  jellyfish,  polyps,  corals. 
Some  drift  with  the  current,  others  settle  down  to  build 
coral  reefs  from  their  limestone  skeletons.  They  have  in- 
sides  for  circulation  and  digestion,  but  their  body  is  built 
on  the  plan  of  a  tub. 

The  next  three  higher  groups,  flatworms,  threadworms, 
wheelworms,  look  like  something;  the  first  two  especially. 
With  them  nature  tried  out  an  epoch-making  experiment — 
bilateral  symmetry:  two  sides,  two  ends.  They  could  tell 
right  from  left  and  knew  whether  they  were  going  ahead 
or  astern.  Good-by  to  the  old  watchful  waiting,  or  drifting- 
round-the-circle  days.    Strenuous  life  moves  straight  ahead. 

Earthworms  seem  low  to  us.  But  a  jellyfish  would  have 
to  look  up  to  them,  they  are  so  highly  organized;  even  an 



amphioxus  respects  them.  They  have  regular  parts;  they 
repair  lost  parts  better  than  a  surgeon.  They  have  a  sug- 
gestion of  a  backbone  and  spinal  cord;  mouth,  esophagus, 
intestine  with  posterior  opening;  nervous  system,  brain  and 
nerve  chain;  pulsating  vessels  to  circulate  the  blood;  kidneys; 
striated  muscle.  If  our  vertebrate  ancestor  was  no  worm,  it 
was  a  worm-like  form.  The  fishworm  has  the  form  and  all 
the  essential  parts.  It  even  has  two  sexes  in  one  body;  it  is 
a  true  hermaphrodite. 

With  molluscs  nature  experimented  with  soft  bodies  pro- 
tected by  shell  armor.  It  was  a  pretty  idea,  and  gave  us 
pearls,  clams,  oysters,  and  snails;  but  the  shells  so  slowed 
them  up  and  weighed  them  down  they  could  never  get  away  to 
a  fast  start  or  far  from  the  mud. 

Starfish  represent  another  experiment.  Possibly  our  deci- 
mal system  is  due  to  the  two  five-fingered  hands  inherited 
from  a  starfish  ancestor. 

Joint-foot  arthropods  are  high  invertebrates.  Some  have 
very  perfect  bodies  and  enough  instincts  to  fill  a  book.  They 
are  segmented  and  have  well-developed  legs — though  neither 
grasshopper,  cricket,  nor  locust  goes  "on  all-four,"  as  Leviti- 
cus misinforms  us.  They  go  on  all  six;  spiders  and  scor- 
pions, on  all  eight. 

That  exhausts  the  possibilities.  But  which  invertebrate 
line  is  founder  of  vertebrates  is  not  yet  determined.  It  may 
have  been  a  fishworm.  It  may  have  been  a  scorpion,  or  a 
horseshoe  crab.  It  may  have  been  an  unknown  family  which 
split,  one  branch  leading  to  the  amphioxus,  which  has  a  real 
notochord,  but  no  skull  and  no  red  blood. 

Poor  fish  as  it  is,  the  amphioxus  is  the  nearest  living  ances- 
tor of  vertebrates.  They  live  a  quiet  life  near  the  shore, 
generally  buried  in  sand  up  to  their  gills.  They  have  the 
makings  of  a  true  fish,  even  to  the  nervous  system;  but  are 
only  a  fish  in  the  making.  And  of  all  the  bodies  nature  tried 
out  during  countless  millions  of  years,  no  survival  has  the 



long,  slender,  segmented  body  that  so  closely  resembles  the 
amphioxus  as  a  fishworm, 


Subkingdom  I,  Protozoa;  subkingdom  II,  Metazoa.  That 
is  all.  Man  belongs  to  the  second  subkingdom:  his  is  a 
many-celled  body,  all  from  an  original  cell. 

Flower  in  crannied  wall  may  be  more  poetic,  but  if  we 
knew  all  about  the  one-celled  ameba,  we  should  know  more 
about  life  than  we  are  likely  to  know  for  some  time.  If  we 
knew  why  several  Protozoa  decided  to  found  a  co-operative 
society  and  so  the  subkingdom  Metazoa,  and  if  we  had  the 
minutes  of  their  first  meeting,  we  should  be  able  to  manu- 
facture animals  to  suit  our  fancy.  If  we  knew  the  nature 
of  the  jelly  called  protoplasm  of  the  ameba's  body,  we  should 
know  what  life  itself  is. 

With  the  mere  mention  of  the  word  "protoplasm"  we  have, 
as  the  farmers  say,  a  lot  of  hay  down.  We  cannot  get  all 
our  "hay"  in  before  it  rains;  some  of  it  spoils.  We  call  in 
the  biochemist,  but  by  the  time  he  gets  it  in  a  test  tube  or 
stains  it  so  that  he  can  see  it,  what  was  living  jelly  is  dead. 
He  examines  only  the  remains — the  "debris,"  as  Lull  calls  it. 

Protoplasm  (first-molded-thing)  is  called  living  jelly  be- 
cause it  is  about  of  the  consistency  of  jelly.  It  is  semi-fluid, 
generally  transparent,  and  colorless.  It  may  contain  granules 
which  make  it  grayish  in  color  and  semi-transparent.  Some 
of  these  granules  may  be  stained,  and  are  called  chromatin. 
This  appears  as  a  central  spherical  mass,  and  is  called  the 
nucleus  {nux,  nut) ;  the  remainder  of  the  protoplasm  is  called 

Protoplasm  is  known  only  by  the  body  it  keeps;  but 
whether  one  cell  is  the  entire  body  or  only  one  in  a  body  of 
billions  of  cells,  every  cell  has  certain  properties  or  func- 
tions. It  is  self-supporting;  it  has  its  own  definite  wall, 
or  is  so  cohesive  that  its  outer  surface  serves  the  purpose  of  a 



wall.  It  eats ;  it  must  have  food  or  it  dies.  It  must  get  rid  of 
waste.  It  moves.  Its  movements  may  be  of  the  flowing  kind 
or  "ameboid" — part  or  parts  of  it  flow  out  in  processes,  like 
the  movements  of  the  ameba.  Or,  it  may  be  covered  in  whole 
or  part  with  fine  cilia  which  set  up  whipping  movements. 
It  is  excitable  or  irritable:  when  touched,  it  moves.  It  re- 
sponds to  certain  stimuli.  It  has  conductivity:  a  stimulus  at 
one  side  may  lead  to  movement  on  the  opposite  side.  It  can 
co-ordinate  its  movements,  as  it  does  in  such  harmonious 
actions  of  the  cilia  or  the  pseudopoda  in  ameboid  move- 
ments.   It  grows  or  has  the  power  of  reproduction. 

The  ameba  can  be  studied  only  under  the  microscope.  It 
is  literally  a  speck  of  living  jelly,  but  it  is  as  "alive"  as  an 
elephant  or  a  whale.  It  goes  about  for  food.  It  flees  from 
danger.  It  is  sensitive  to  stimuli  from  without.  It  breathes 
oxygen  and  gives  off  carbon  dioxide;  collects,  digests,  and 
distributes  food;  excretes  waste;  reproduces  its  kind.  It  can 
learn  from  experience.  It  is  organized  for  one  purpose  only: 
life.    Within  that  limit  it  fails  in  no  essential. 

What  is  the  ameba?  Life.  What  is  life?  Protoplasm — 
ultramicroscopic,  unanalyzable ;  but  only  living  if  it  behaves 
like  a  living  being. 

Protoplasm  is  72  per  cent  oxygen,  13.5  per  cent  carbon, 
9.1  per  cent  hydrogen,  and  2.5  per  cent  nitrogen.  The  re- 
maining 3  per  cent  consists  of  sulphur,  phosphorus,  chlorine, 
sodium,  potassium,  calcium,  magnesium,  iron,  and  silicon. 
Add  a  pinch  of  fluorine,  iodine,  and  manganese;  and  that  is 
what  little  girls  are  made  of. 

Such  is  the  stuff"  of  life.  How  about  the  staff"  of  life?  For, 
as  Huxley  said,  while  a  solution  of  smelling  salts  in  water, 
with  a  tiny  pinch  of  some  other  saline  matter,  contains  all 
the  elements  which  make  up  protoplasm,  a  hogshead  of  that 
fluid  would  not  keep  a  hungry  man  from  starving,  nor  save 
any  animal  from  like  fate.  It  is  equally  true  that  if  animals 
lived  only  on  dead  animals,  the  animal  world  would  perish 



through  cannibalism.  Even  nature  cannot  pull  herself  up 
by  her  bootstraps. 

Which  takes  us  out  into  the  open  and  face  to  face  with  life 
itself.  No  one  quite  knows  what  life  is,  but  there  are  certain 
fairly  accurate  tests  for  life.  One  is  growth.  Are  certain 
bacteria  alive?  Put  them  in  a  suitable  medium:  if  they  grow, 
they  are  alive;  if  not,  they  are  dead.  We  stop  growing 
larger,  but  when  there  is  no  growth  anywhere  in  our  body 
we  are  dead  and  our  own  digestive  juices  will  begin  to  digest 
our  body. 

The  point  is  that  plants  are  older  than  animals  and  bacteria 
older  than  both;  and  that  there  is  no  sharp  line  between  lowest 
animals  and  lowest  plants  or  any  general  agreement  as  to 
whether  bacteria  are  plants  or  animals.  Nor  does  it  make  any 
particular  difference  to  us.  What  matters  is  that  animals 
must  rely  on  plants  or  other  animals  for  their  growth-material 
and  that  plants  are  not  so  dependent;  they  can  live  on  mate- 
rials which  would  be  death  to  animals.  With  carbon  dioxide, 
water,  and  nitrogenous  salts,  a  plant  will  multiply  a  billion- 
fold — "building  up  the  matter  of  life  from  the  common 
matter  of  the  universe."  But  where  do  they  get  their  nitro- 
genous salts? 

Bacteria.  Their  daily  bread  is  a  few  simple  minerals. 
Without  bacteria,  air,  land,  and  ocean  to-day  would  be  life- 
less. They  were  the  primordial  chemists,  finding  food  in  a 
foodless  world,  drawing  their  energy  and  their  nutrition 
direct  from  lifeless  compounds.  We  shall  have  a  closer  look 
at  them  later.  It  is  enough  now  to  pay  a  tribute  to  them 
for  having  helped  form  the  crust  of  the  earth  and  so  prepare 
the  land  and  sea  for  the  evolution  of  higher  life.  Without 
them,  life  on  earth  as  we  know  it  is  inconceivable,  nor  would 
life  be  possible  to-day  without  them. 

In  other  words,  this  earth  was  once  lifeless  and  about  as 
big  as  Mars,  half  its  present  size.  To  imagine  it  as  it  was 
then,  Osborn  asks  us  to  subtract  all  mineral  deposits  of 
organic  origin,  such  as  organic  carbonates,  phosphates,  and 



lime;  carbonaceous  shales  and  limestones;  graphites;  silicates 
derived  from  diatoms;  iron  deposits;  humus  of  the  soil;  soil 
derived  from  rocks  broken  down  by  bacteria;  and  ooze  of  the 
ocean  floor.  The  shells  of  microscopically  small  diatoms 
alone  make  up  6  per  cent  of  the  bottom  of  ten  million  square 
miles  of  sea! 

These  organic  deposits  cover  the  earth  miles  deep.  They 
fitted  it  for  higher  forms  of  life.  And  all  due  to  microorgan- 
isms. Geikie  thinks  it  might  have  required  four  hundred 
million  years. 


The  earth  itself,  according  to  Chamberlin,  our  foremost 
geologist,  is  an  offspring  of  the  sun;  as  are  the  other  seven 
planets,  the  twenty-six  satellites,  and  the  eight  hundred  planet- 
oids which  make  up  our  planetary  system.  In  giving  birth 
to  them,  the  sun  parted  with  less  than  an  eight-hundredth  part 
of  its  body,  the  earth  itself  representing  about  three-thou- 
sandths of  1  per  cent  of  the  sun's  substance.  In  other  words, 
our  earthly  home  is  considerably  less  than  the  proverbial  drop 
in  the  bucket  of  our  heavenly  parent. 

Birth  of  earth  and  other  planets  was  due  to  a  passing  star. 
It  was  bigger  and  denser  than  the  sun  and  consequently  had 
a  greater  pull.  It  attracted  little  bits  of  the  sun  away.  One 
bit  is  our  earth,  held  to  its  course  by  pull,  by  gravity.  Were 
the  pull  of  the  sun  to  be  altered,  the  orbit  our  earth  makes 
about  the  sun  would  change. 

It  happened  this  way.  The  sun  is  so  hot  that  it  explodes 
sun-stuff  or  gas-bolts.  They  travel  300  miles  a  second  and 
may  project  300,000  miles  beyond  the  sun's  surface  before 
they  drop  back  again. 

Along  came  a  huge  star,  itself  a  sun,  bigger,  denser,  than 
our  little  sun.  Its  pull  was  so  great  that  the  sun  stuff  that 
happened  to  be  erupting  was  drawn  so  far  out  it  could  not 
fall  back.  It  was  mostly  gas,  the  parts  nearest  the  sun  hottest. 



It  kept  on  moving,  condensing;  it  came  finally  to  be  broken 
up  into  bits.  Each  bit  kept  on  traveling  in  its  own  orbit  about 
the  sun — ^held  by  the  sun's  pull,  but  each  too  distant  to  be 
pulled  back  into  the  sun. 

Chamberlin  assumes  that  several  gas-bolts  were  pulled 
from  the  sun.  From  the  first  grew  Neptune  and  Uranus; 
from  the  second,  Saturn  and  Jupiter.  These  great  planets 
are  still  hot  and  gaseous.  On  the  return  journey  the  pass- 
ing star  loosed  another  gas-bolt;  from  it  grew  the  terrestrial 
planets:  Earth,  Venus,  Mars,  and  Mercury. 

The  earth  to-day  is  five  and  one-half  times  heavier  than 
an  equal  volume  of  water.  At  first  it  y/as  not  so  dense, 
more  nebulous,  and  of  varying  density.  Knots  of  denser 
matter  condensed  into  liquid  or  solid  cores.  These  grew  by 
drawing  into  themselves  smaller  knots.  This  could  happen 
because  their  orbits  kept  changing  according  to  their  change 
in  density.  The  largest  core  kept  on  picking  up  bits  that 
came  in  its  path.  It  kept  on  growing  denser.  The  earth  is 
still  growing. 

When  only  a  nebulous  knot,  the  earth  was  magnetic,  and 
is  now.  It  "selected"  the  matter  that  was  to  form  its  core: 
iron,  nickel,  cobalt.  It  picked  up  planetesimal  dust,  meteor- 
ites, etc.  It  began  to  draw  an  atmosphere  about  it.  From 
the  atmosphere  fell  the  rain,  the  primitive  waters  in  the  earth's 
cavities.  Thus  there  came  to  be  a  lithosphere,  a  hydrosphere, 
an  atmosphere. 

Our  atmosphere  is  chiefly  nitrogen,  oxygen,  hydrogen,  and 
water-vapor;  all  were  in  the  original  nebulous  knot.  Some 
gases  were  carried  into  the  inside  of  the  earth,  to  be  let 
loose  again  by  volcanic  action.  Some  simply  gathered  more 
and  more  closely  about  the  earth;  the  earth's  pull  was  enough 
to  hold  them. 

When  the  young  earth  had  reached  30  per  cent  of  its 
growth,  it  could  begin  to  draw  to  it  the  water-vapor  that  had 
been  shot  from  the  sun.  Thereafter,  the  water  on  the  earth 
and  in  the  atmosphere  strove  to  maintain  an  equilibrium.  But 



the  temperature  kept  changing  and  the  atmosphere  kept  cir- 
culating. The  earth  has  always  had  its  arid  as  well  as  its 
humid  areas;  it  was  never  enveloped  in  a  "warm  moist  atmos- 

Our  earth  began,  then,  with  a  small  lithosphere,  a  small 
hydrosphere,  a  small  atmosphere.  These  reacted  on  each 
other,  always  in  co-operation,  always  in  competition  and  an- 
tagonism. Even  to-day  land,  water,  and  air  struggle  for  the 
mastery.  The  story  of  that  struggle  is  the  history  of  the 
earth.  The  oldest  rock  record  known  shows  that  the  earth 
was  then  about  as  it  is  to-day,  mostly  land  areas,  wide  seas. 
Water  and  air  struggle  to  wear  the  land  down,  only  to  have 
it  buckle  up  again  in  some  new  mountain  range,  the  waters  to 
retire  to  new  abysmal  depths. 

As  long  as  volcanoes  last,  the  earth  will  not  get  over- 
heated because  of  pressure  toward  the  core.  Through  vol- 
canoes, as  through  the  pores  of  our  skin,  the  earth  rids  itself 
of  excess  heat  and  fluids.  Thus,  the  earth  is  always  becoming 
more  solid,  more  rigid ;  its  lighter  and  more  mobile  material 
is  constantly  being  forced  to  the  surface,  again  to  be  buried, 
reheated,  reorganized,  and  part  of  it  to  be  belched  forth 
again.  Its  core  now  is  chiefly  metallic,  its  envelope  of  a 
fluid-like  nature;  the  whole,  immobile,  refractory,  crystalline. 

The  gas-bolt  that  was  pulled  by  a  passing  star  from  its 
parent  sun  and  grew  into  earth  carried  the  elements  of  life. 
When  the  earth  was  fit  for  life,  life  came;  the  inorganic 
elements  reorganized  into  organic  compounds.  That  was  as 
radical  a  move  in  the  earth's  evolution  as  was  its  break  from 
the  sun. 


With  the  words  we  build  with  our  A  B  C's  we  name  the 
universe  nature  builds  with  her  L  M  N's — as  the  Romans 
called  them,  from  the  letters  on  the  tablets  on  which  children 
learned  to  write.   The  world  of  matter  is  what  it  is  because 



the  elements  are  what  they  are  and  what  they  become  when 
chemically  united.  Each  element  is  unique  and  has  unique 
behavior,  but  matter  assumes  an  infinite  variety  of  forms 
because  two  or  more  elements  can  surrender  their  individ- 
uality and  become  a  new  substance  with  unique  behavior. 

A-r-w  is  a  meaningless  mixture  of  letters ;  w-a-r  is  a  loaded 
word  and  has  infinite  possibilities.  With  only  two  elements, 
thousands  of  new  substances  are  possible;  with  three,  the 
possible  combinations  are  enormously  increased.  With  C,  H, 
0,  and  N,  and  a  pinch  of  salts,  every  living  thing  is  possible. 

Why?    It  is  their  nature. 

"Nature"  can  mean  anything.  For  example,  sodium  is  a 
metal,  lighter  than  water;  a  drop  of  it  on  our  tongue  or  on  a 
sweaty  hand  catches  fire  and  burns  a  hole.  Chlorine  is  a 
gas,  heavier  than  air,  so  corrosive  that  a  few  whiff's  are  fatal; 
it  was  the  poison  gas  in  the  World  War.  Of  these  two  ele- 
ments combined  in  one,  we  use  about  thirty  million  tons  a 
year.  It  is  found  on  every  table,  eaten  at  every  meal. 
Sodium  chloride  is  common  everyday  table  salt:  in  large 
quantities,  fatal;  in  moderate  amounts,  good  for  man  and 

What  is  the  nature  of  salt?  Why  do  we  require  a  certain 
amount  of  salt  in  our  diet?  Why  will  salt  preserve  meat? 
Why  do  sodium  and  chlorine  lose  their  specific  characters 
when  united  as  salt?  Why  is  sodium  electrically  positive, 
chlorine  negative?  Why  is  the  human  body  rubbed  with 
wool  positively  charged;  rubbed  with  silk,  negatively 
charged?    What  is  the  nature  of  electricity? 

The  nature  of  things  is  what  we  know  of  things.  Of  some 
we  have  the  number,  we  know  their  law.  For  example,  with 
hydrogen,  chlorine  forms  hydrochloric  (muriatic)  acid,  so 
strongly  caustic  that  it  will  eat  the  enamel  off  a  tooth  or 
dissolve  a  bone.  Dogs'  stomachs  secrete  more  hydrochloric 
acid  than  ours;  they  digest  bones  better  than  we  do.  Why 
our  stomach  secretes  hydrochloric  acid  is  one  question;  how 
our  body  separates  the  chlorine  out  of  salt  and  the  hydrogen 



from  water  (both  difficult  chemical  processes)  and  com- 
bines them  into  a  powerful  acid  that  will  digest  gristle,  is 
another.  The  first  question  is  on  a  par  with  thousands  of 
others  as  yet  beyond  the  pale  of  science. 

What  is  the  nature  of  elements?  The  answer  is  so  astound- 
ing that  the  world  has  hardly  yet  recovered  its  breath,  so 
far-reaching  in  its  implications  that  science  has  not  yet 
grasped  its  full  significance. 

Science  recognizes  eighty-two  and  actually  knows  seventy- 
nine  stable  elements.  There  are,  in  addition,  ten  heavy 
radioactive  elements,  which,  unlike  the  stable  elements,  are 
transmuting  themselves  into  lighter  elements. 

The  unit  or  smallest  quantity  of  an  element  which  takes 
part  in  a  chemical  reaction  is  an  atom  (uncutable). 
Recently,  the  atom  has  been  "cut."  It  consists  of  unit 
charges  of  positive  and  negative  electricity  called  electrons. 
While  electrons  are  alike  in  strength  of  electric  charge,  nega- 
tive electrons  have  a  mass  or  inertia  l/1845th  of  the  lightest 
known  atom,  hydrogen.  In  other  words,  the  weight  of  the 
negative  as  compared  with  the  positive  electron  is  almost 

An  atom,  then,  says  Millikan,  consists  of  a  heavy  core  or 
nucleus  of  free  positive  electrons  about  which  are  grouped 
enough  negative  electrons  to  render  the  whole  atom  stable 
or  neutral.  "Hence  the  number  of  negative  electrons  out- 
side the  nucleus  must  be  such  as  to  have  a  total  charge  equal 
to  the  free  positive  charge  of  the  nucleus;  otherwise  the 
atom  could  not  be  neutral."  As  the  weight  of  the  atom 
depends  almost  entirely  upon  its  nucleus,  and  as  hydrogen  is 
the  lightest  element,  the  atomic  weight  of  other  elements  is 
an  expression  of  their  weight  compared  with  that  of 

The  atomic  number  of  hydrogen  is  1.  Its  nucleus  carries 
one  electron  of  positive  charge;  outside  that  nucleus  is  one 
electron  of  negative  charge.  The  two  electrons  thus  neu- 
tralize each  other;  the  result  is  a  system,  an  atom  of 



hydrogen.  The  heaviest  known  element  is  uranium;  its 
atomic  weight  is  238.  Its  nucleus,  therefore,  must  contain 
238  positive  electrons.  But  as  its  atomic  number  is  92,  its 
nucleus  must  carry,  in  addition,  146  negative  electrons  to 
neutralize  the  146  positive  electrons  over  and  above  the  92 
positive  electrons  free  to  neutralize  the  92  negative  electrons 
outside  the  nucleus.  The  result  is  a  system,  an  atom  of 
uranium.  Remove  one  free  positive  electron  from  the 
nucleus  of  that  atom;  it  is  no  longer  an  atom  of  uranium. 
Remove  10  free  positive  electrons;  it  is  an  atom  of  lead. 
Remove  13;  it  is  an  atom  of  gold.  Remove  91;  it  is  an 
atom  of  hydrogen  gas.  The  92  elements  are  determined, 
says  Millikan,  simply  by  the  difference  between  the  number 
of  positives  and  negatives  packed  into  the  nucleus.  All 
elements,  ideally  at  least,  are  transmutable  into  one  another 
by  a  simple  change  in  this  difference. 

Magnify  the  nucleus  of  an  atom  one  billion  times;  it  is 
still  too  small  to  be  seen  in  a  microscope.  Multiply  that 
nucleus  ten  billion  times:  the  outer  electrons  are  now  three 
feet  from  the  nucleus,  but  the  nucleus  itself  is  not  yet  as  big 
as  a  pin-point.  The  nucleus,  then,  is  less  than  1/10,000 
the  diameter  of  the  atom — and  yet  it  may  contain,  as  does 
the  uranium  atom,  384  electrons.  No  wonder  that  Millikan 
can  shoot  helium  atoms  by  the  billion  through  a  thin  glass 
evacuated  tube  "without  leaving  any  holes  behind."  Atoms 
themselves  are  mostly  "holes,"  as  is  most  of  our  solar  system. 
The  negative  electron  compared  with  the  size  of  the  atom 
itself  is  no  larger  than  is  the  earth  compared  with  the  radius 
of  its  orbit  about  the  sun.  And  yet  atoms  themselves  are 
"infmitely  small" !  Electrons  must  be  infinitely  smaller.  Or 
rather,  smallest  conceivable — for  the  electron  itself  is  now 
believed  to  be  the  indivisible,  ultimate  unit  of  matter. 

When  matter  in  the  form  of  an  electron  moves,  there  is  an 
electric  current.  Which  means,  says  Millikan,  that  electricity 
and  matter  look  like  different  aspects  of  one  and  the  same 



thing.  There  is  proof  that  electricity  is  material;  there  is 
evidence,  but  not  yet  proof,  that  all  matter  is  electrical. 

The  electron  itself,  then,  is  a  speck  of  electricity;  it  has 
definite  granular  structure;  it  is  the  primordial  stuff  of  the 
universe  of  matter.  When  specks  of  electricity  are  combined 
in  certain  ways  and  proportions,  certain  neutral  systems 
result,  and  we  have  the  atoms  of  the  elements  of  all  physical 
bodies  which  are  described  in  terms  of  chemistry  and 
physics — matter  and  energy. 

Science  knows  nothing  of  the  ultimate  origin  of  matter 
or  of  the  source  of  energy;  it  only  accepts  both  as  facts  and 
goes  on  with  its  business  of  trying  to  find  out  what  matter 
is  and  what  energy  can  do.  In  other  words,  the  problem  of 
the  origin  of  life  is  locked  up  in  the  origin  of  matter  and 
in  the  nature  of  energy.  But  the  line  between  life  and  death 
is  not  unlike  that  between  organic  and  inorganic,  a  vague 
shadowy  line  crossed  from  day  to  day  in  the  chemical  labora- 
tory. Life  has  been  produced  in  no  man-made  shop;  proto- 
plasm, the  chemical  matter  of  life,  has  been.  It  does  every- 
thing but  live!    It  does  not  seem  fit  for  life. 


Life  cannot  live  without  food.  Food  cannot  be  had  in  a 
red-hot  sun,  in  the  interior  of  the  earth,  or  in  a  nebula  of  gas. 

We  hear  much  of  "fitness,"  but  always  the  fitness  of  the 
organism.  There  is  another  fitness — that  of  the  earth  itself. 
Before  trees,  there  was  no  arboreal  life;  before  plants,  no 
animals.  Only  as  the  fitness  of  the  environment  evolved 
could  life  evolve.  Environment  and  life  go  together.  Fit- 
ness of  environment  is  as  essential  to  life  as  it  is  to  a  snow- 
flake,  a  salt  crystal,  a  diamond,  or  a  river;  nor  are  these 
more  thinkable  out  of  their  environment  than  is  any  living 
being,  or  more  easily  "explained"  away.  The  fitness  of  ihe 
earth's  environment  for  life  has  been  beautifully  worked  out 
by  Henderson. 



The  earth  keeps  its  atmosphere  because  of  its  size  and 
relation  to  the  sun.  This  fact  and  the  nature  of  its  atmosphere 
led  to  winds  and  clouds,  rain,  snow  and  ice,  lakes  and  rivers, 
oceans  and  ocean  currents,  tides,  and  magnetic  and  electric 

In  the  earth's  atmosphere  were  carbon,  hydrogen,  and 
oxygen.  From  carbon  and  oxygen  came  carbon  dioxide; 
from  hydrogen  and  oxygen,  water.  With  water,  carbon 
dioxide,  and  carbon  compounds,  living  things  became  pos- 
sible.   These  three.    The  greatest  of  these  is  water. 

There  is  nothing  like  water.  Over  seventy  per  cent  of  our 
body  weight  is  water.  Much  of  life  lives  in  water  and  all 
of  life  dries  up  without  water.  No  water,  no  life.  Life  as 
we  know  it  is  inconceivable  without  water.  In  fact,  Prout, 
the  theologian,  thought  it  the  most  remarkable  instance  of 
"design"  in  all  nature:  "Something  done  expressly,  and 
almost  (could  we  conceive  such  a  thing  of  the  Deity)  at 
second  thought,  to  accomplish  a  particular  object." 

Why  does  the  highly  inflammable  gas  hydrogen,  united  in 
certain  proportions  to  oxygen,  another  gas  and  necessary  for 
combustion,  always  produce  water,  which  is  not  only  not 
inflammable,  but  a  hindrance  to  combustion?  The  "why" 
of  water  is  unknown.  Much  is  known  of  its  behavior,  in 
some  respects  more  weird  than  that  of  a  child.  We  speak 
of  "solving"  problems.  Water  is  the  great  solvent.  We  may 
not  suff'er  from  water  on  the  brain,  but  conscious  brains  are 
85  per  cent  water.  Were  our  brains  only  60  per  cent  water, 
they  would  be  as  dense  as  tendons;  if  only  20  per  cent,  as 
hard  as  the  skull  itself;  and  if  10  per  cent,  just  fat. 

More  substances  will  dissolve  in  water  than  in  any  other 
liquid.  Each  year  the  earth's  rivers  carry  to  the  sea  five 
billion  tons  of  dissolved  minerals  and  other  unnumbered 
millions  of  tons  of  carbon  compounds.  Water  is  the  great 
dissolvent  of  food  before  it  is  taken  into  the  cells  and  as  it 
leaves  the  body  through  the  sweat  glands,  kidneys,  or  lungs. 
Over  90  per  cent  of  the  blood  of  our  transport  system  is 



water,  holding  in  solution  iodine,  bromine,  iron,  sulphates, 
urea,  ammonia,  etc.  The  water  excretion  of  our  body  carries 
off  in  solution  countless  organic  substances,  as  well  as 
chlorides,  bromides,  iodides,  phosphates,  potassium,  sodium, 
ammonia,  magnesium,  iron,  carbon  dioxide,  nitrogen,  argon, 

Chemical  reactions  take  place  in  water;  electrical  forces 
are  at  work,  forces  which  bind  atoms  into  molecules  and 
cause  chemical  reactions.  Acids  and  salts  are  electrolytes: 
they  can  carry  electric  currents,  they  can  be  dissolved  by 
electric  currents.  In  dissolution,  ions  (goings)  are  formed; 
they  carry  the  current. 

Life  is  dynamic.  Every  living  thing  is  a  dynamo.  Its 
electricity,  like  that  of  batteries,  comes  from  the  ions  of 
atoms  of  electric  charge  set  free  when  molecules  of  acids, 
bases,  and  salts  are  split  up.  Ions  are  back  of  protoplasm 
and  essential  to  all  life  processes.  Water  is  the  supreme 
solvent  for  ionization. 

A  heart  cut  from  a  living  body  keeps  right  on  beating 
provided  it  is  kept  in  proper  solution.  What  is  "proper" 
for  a  heart?  A  change  in  the  hydrogen  ion  concentration 
of  one  ten-billionth  part  in  that  solution  is  improper:  the 
heart  stops.  The  control  over  such  salt  solutions  is  now  so 
perfect  that  glands  can  be  kept  alive  while  awaiting  trans- 
plantation into  foreign  bodies. 

Water  is  chemically  and  physically  stable;  inert  in  the 
atmosphere;  almost  inactive  on  the  surface  and  in  the  soil. 
It  changes  few  substances,  it  is  not  easily  changed.  It  is 
almost  everyv/here  present  in  the  soil ;  and  in  the  atmosphere 
as  clouds  and  vapor.  Its  high  specific  heat  tempers  both 
summer  and  winter.  The  tropics  is  a  vast  warm  reservoir; 
the  poles,  cold  reservoirs.  This  m.akes  for  circulation  of  the 
atmosphere  and  ocean  currents.  Water's  high  specific  heat 
also  makes  it  possible  for  man  to  produce  2,400  calories 
a  day,  enough  to  raise  his  temperature  to  150  degrees,  and 
yet  keep  his  body  at  its  normal  temperature. 


Water  can  be  cooled  to  the  freezing  point;  it  can  get  no 
colder  than  ice.  With  the  thermometer  forty  degrees  below 
zero,  a  cake  of  ice  is  almost  the  next  best  thing  to  a  stove. 
Lakes  and  oceans  cannot  get  colder  than  the  freezing  point 
of  water.  This  makes  water  a  powerful  regulator  of  the 
earth's  temperature. 

Most  substances  contract  with  cold.  If  water  obeyed  this 
law,  most  of  life  would  go  out  of  business  every  winter. 
Water  loses  density  on  cooling;  it  rises  to  the  top.  Lakes 
and  rivers  freeze  from  the  top  down,  not  from  the  bottom  up. 

Life  is  colloidal,  like  glue,  jelly,  protoplasm;  it  has  no 
definite,  rigid,  predetermined  form,  as  has  a  crystal.  Colloid 
structures  are  complex  beyond  man's  present  capacity  to 
resolve  them  when  in  the  form  of  protoplasm.  Protoplasm 
can  live  because  it  can  absorb  food  substances.  The  force 
which  operates  upon  colloidal  structure  is  surface  tension  of 
water.    Surface  tension  is  at  the  root  of  all  food  metabolism. 

In  short,  water  is  a  vital  part  of  the  evolutionary  process 
which  fitted  the  earth  to  be  the  home  of  the  life  that  culmi- 
nates in  man;  fit  of  its  very  nature,  as  Henderson  says, 
"with  a  fitness  no  less  marvelous  and  varied  than  that  fitness 
of  the  organism  which  has  been  won  in  the  course  of  organic 

Every  living  thing  is  but  a  v/atery  solution;  man  himself, 
but  a  porous  sack  of  water.  But  water  alone  could  not  have 
led  to  life  without  carbon  dioxide.  Carbon  dioxide  is  even 
more  pervasive  than  water;  it  is  everywhere. 

Carbon  dioxide  (carbonic  acid  or  carbonic  acid  gas — one 
atom  of  carbon,  two  of  oxygen)  is  colorless,  has  an  acid 
taste,  a  pungent  smell.  Inhaled  by  animals,  death  follows 
from  asphyxiation.  Eaten  by  animals,  in  the  sugars  and 
starches  of  plants,  it  "burns";  what  is  left  over  is  carbon 
dioxide.  Were  it  not  a  gas,  the  task  of  ridding  the  body 
of  it  would  be  impossible;  were  it  not  a  freely  soluble  gas, 
that  task  again  would  be  impossible. 

Only  carbon  dioxide  enters  water  as  freely  as  it  escapes 



from  water.  As  water  is  made  up  of  hydrogen  and  oxygen 
so  firmly  wedded  that  only  unusual  force  tears  them  apart, 
so  water  and  carbon  dioxide  are  inseparable  companions: 
in  water  itself,  in  fire,  in  air,  in  the  earth.  Only  its  unique 
mobility  and  its  wide  distribution  have  made  plant  life 

The  lilies  of  the  field  toil  not;  the  sun  does  it  for  them, 
using  carbon  dioxide  of  the  air  and  of  the  water.  The 
cattle  of  the  field  have  to  go  to  the  lilies:  the  lilies  will  not 
come  to  them.  Cattle  toil  with  the  sun's  energy  of  green 
grass.  We  too  are  children  of  the  sun  and  toil  with  its 
energy  stored  in  food  plants.  For  example,  a  gram  of 
glucose  contains  3.7  heat  units  of  solar  energy.  When  a 
muscle  burns  that  gram,  the  3.7  units  are  spent:  the  glucose 
was  a  temporary  depository  of  energy.  The  energy  was 
released  by  burning,  oxidation. 

Glucose  is  a  carbohydrate — C6H12O6.  Ninety-five  per  cent 
of  our  body  can  be  accounted  for  by  these  same  symbols — 
C  H  0;  for  water,  we  need  only  hydrogen  and  oxygen;  for 
carbon  dioxide,  only  carbon  and  oxygen. 

When  heat  and  energy  were  liberated  from  glucose,  the 
oxygen  was  torn  from  the  carbon  and  hydrogen.  Oxygen 
is  almost  unique  in  its  energy-liberating  processes.  Com- 
pounds of  carbon,  and  especially  of  hydrogen,  yield  great 
heat  in  oxidation.  No  source  of  energy  so  good  as  oxygen. 
No  transformers  of  energy  so  great  as  hydrogen  and  carbon. 
Together,  these  three  elements  have  unique  "fitness  for  the 
organic  mechanism.  They  alone  are  best  fitted  to  form  it 
and  set  it  in  motion;  and  their  stable  compounds,  water  and 
carbon  dioxide,  which  make  up  the  changeless  environment, 
protect  and  renew  it,  forever  drawing  fresh  energy  from  the 

Water  is  not  an  organism;  it  is  not  life;  it  is  inorganic. 
Carbon  dioxide  is  not  an  organism;  it  is  not  life;  but  it  is 
organic.  The  carbon  makes  the  vital  diff"erence.  Protoplasm 
is  a  very  wonderful  substance.    Remove  its  carbon:   it  is 



no  longer  protoplasm ;  it  is  not  even  an  "organic"  compound. 
The  chemist  does  not  "wonder"  about  protoplasm;  he  finds 
carbon  wonderful  enough. 

What  is  carbon?  The  lead  in  the  pencil  with  which  I 
write,  for  one  thing.  Charcoal  is  carbon.  So  is  lampblack. 
Also  diamonds.  What  is  an  element?  A  system.  Each  atom 
of  each  element  is  a  system.  Carbon  must  be  thought  of  as 
having  form,  shape,  size,  mass,  architecture.  Build  atoms 
of  carbon  one  way,  and  you  have  a  molecule  of  diamond; 
another  way,  and  you  have  a  molecule  of  lampblack.  Carbon 
alone  among  the  elements  can  form  the  skeleton  of  the  com- 
pounds known  to  organic  chemistry.  It  is  a  unique  sub- 
stance; in  its  way,  as  unique  as  life  itself.  It  is  unique 
in  its  capacity  to  enter  into  relationships  with  other  elements. 
One  atom  of  carbon  can  unite  with  from  one  to  four  other 
atoms  to  form  a  compound.  Carbon  atoms  can  form  ring 
compounds,  the  rings  themselves  may  unite  with  carbon 
chains,  and  so  on  in  bewildering  possibilities.  With  only 
fourteen  atoms  of  carbon  and  thirty  of  hydrogen,  it  is  possi- 
ble to  form  1,855  distinct  and  stable  compounds.  The 
difference  between  acetylene  and  paraffin  is  in  the  way  their 
carbon  and  hydrogen  atoms  are  combined. 

Add  oxygen  to  carbon  and  hydrogen:  the  number  of 
organic  compounds  possible  is  at  once  multiplied  enormously. 
Alcohol,  glycerine,  lactic  acid,  ether,  carbolic  acid,  sugar, 
cotton,  camphor,  olive  oil,  starch,  oil  of  wintergreen,  vanilla, 
and  the  venom  of  the  cobra.  What  a  mess — solids,  liquids, 
gases!  Yet  only  three  elements  enter  into  their  make-up: 
carbon,  hydrogen,  oxygen.  The  list  only  suggests  the 
diversity  that  follows  from  a  few  of  the  thousands  of  possible 
combinations  of  three  seemingly  simple  chemical  elements. 

About  a  half-million  organic  compounds  are  already 
known  to  chemists.  Back  of  all,  carbon.  Hydrogen  and 
oxygen,  next  in  importance.  These  three  made  life  possible: 
as  water,  the  carrier  of  life ;  as  carbon  dioxide,  the  substance 
on  which  life  hangs. 



From  such  simple  carbon  compounds  as  the  baby  earth 
inherited  from  parent  sun,  grew  the  more  complex  and 
subtle  carbon  compounds  that  to-day  peer  into  microscopes 
at  dividing  cells  and  shake  test  tubes  over  gas  jets  to  discover 
what  life  is. 

The  earth's  physical  conditions  were  always  changing. 
Matter  itself  kept  changing.  Earth,  energy,  matter,  are 
bound  together  in  one  continuous  change:  the  history  of 
that  change  is  the  story  of  evolution.  In  the  process  of 
change  life  itself  was  evolved.  But  only  after  the  environ- 
ment into  which  life  fits  itself  had  evolved  to  the  point  that 
it  was  fit  for  life.  Fitness  of  life  and  fitness  for  life  are 
two  views  of  the  same  tale;  and  both  incidents  in  the  greater 
story  which  goes  back  through  the  young  earth  to  the  old 
sun,  and  thence  out  into  the  wide  universe.  Forward,  to 


Snowflake,  salt  crystal,  diamond,  are  described  in  terms  of 
matter  and  energy;  explained  in  no  terms  known  to  science. 
Life  also  is  described  in  terms  of  matter  and  energy.  The 
form  or  substance  of  life  is  complex,  much  more  complex 
than  snowflake,  salt  crystal,  or  diamond. 

This  complexity  of  living  beings  requires  a  mechanism 
organized  for  durability.  The  lowest  plant  is  a  more  com- 
plex mechanism  than  is  a  raindrop,  a  snowflake,  or  a  crystal. 
But,  like  them,  living  beings  are  subject  to  gravity,  and  if 
they  break  the  laws  of  physics  and  chemistry  they  no  longer 
live:  what  was  complex  and  had  a  certain  behavior  is  now 
less  complex  and  has  a  different  behavior. 

Living  things  escape  the  fate  of  less  complex  compounds 
by  holding  their  fate  in  their  own  hands  to  an  extent  denied 
inorganic  things.  Snowflake  and  bacterium  "die"  under  a 
sun's  ray;  an  alga  synthesizes  protoplasm;  a  lizard  crawls 
into  the  shade;  a  man  hoists  an  umbrella.  But  one  action 
is  no  more  "explicable"  than  the  other. 



The  lizard's  energy  is  of  a  different  type  from  that  of  the 
bacterium;  it  has  a  wider  range,  it  can  better  adapt  itself 
to  its  environment.  But  otherwise  its  vital  processes,  though 
of  a  higher  order,  must  be  of  the  same  kind. 

Life,  in  any  and  all  forms,  to  go  on  as  life,  must  exchange 
matter  and  energy  with  its  environment;  it  takes  in  food, 
excretes  waste. 

The  smallest  known  molecule — hydrogen — weighs  a  three- 
million-million-million-millionth  of  a  gram.  It  travels  a  mile 
a  second.  Do  chemistry  and  physics  "resolve"  it?  An 
electron  is  smaller  and  travels  faster.  Is  it  less  mysterious 
than  a  seed  of  mignonette?  Why  does  a  molecule  of  hydro- 
gen have  only  one  kind  of  behavior,  a  molecule  of  oxygen 
two  kinds,  a  molecule  of  carbon  four  kinds?  Heredity? 
Why  does  one  speck  of  protoplasm  grow  into  mignonette, 
another  into  man?  Heredity  again.  But  always:  matter, 
energy.  The  matter  is  differently  combined,  the  energy 
comes  from  different  sources. 

Thus,  plants  obtain  such  matter  as  carbon  dioxide,  water, 
and  mineral  salts,  from  the  air  and  soil.  With  the  aid  of 
energy  (sunlight)  they  transform  these  into  such  other 
matter  as  sugar  and  oxygen.  The  oxygen  returns  to  air 
and  renews  it.  What  becomes  of  the  solar  energy?  Animals 
eat  the  sugar;  within  their  body  it  is  burned,  setting  free  as 
muscular  force  and  heat  the  energy  the  plant  got  from  the 
sun.  What  becomes  of  the  by-products?  Eliminated  by 
the  animal  as  carbon  dioxide  and  water:  food  fit  for  plants. 
The  food  goes  round  and  round. 

Living  matter  does  not  produce  something  out  of  nothing, 
neither  the  matter  of  its  own  body  nor  the  energy  expended 
in  building  its  body  or  in  keeping  it  alive.  Plants  conserve 
energy,  animals  dissipate  it. 

Nothing  is  destroyed,  nothing  lost.  Wliat  is  here  has 
always  been  here,  or  gathered  up  from  the  dust  of  the 
universe.  Energy  from  the  sun  changes  matter,  alters  it, 
evolves  it.    Matter  itself  is  indestructible;  the  energy  itself 



is  transformed,  flows  in  but  one  direction.  There  is  enough 
in  the  sun  to  keep  earth  and  life  going  for  untold  millions 
of  years. 

Untold  millions  of  years  ago,  the  sun's  rays  were  impelling 
forces  as  they  are  to-day.  Under  their  influence,  the  facile 
carbon  took  on  new  and  more  complex  forms  as  it  built  into 
its  structure  hydrogen,  oxygen,  nitrogen,  sulphur,  phosphorus, 
chlorine,  sodium,  potassium,  calcium,  magnesium,  and  iron. 

This  took  time.  But  the  times  were  ripe  when  water  began 
to  collect  in  pools,  and  there  were  shores.  Circulation,  at 
any  rate,  went  on  then.  Evaporation  made  for  clouds :  water 
came  from  above;  capillary  attraction  brought  the  waters 
up  from  below.  Wet  and  dry  seasons  alternated.  The 
elements  favored  concentrations  and  resolutions.  All  favor- 
able to  colloidal  growth,  to  fluent  forms,  and  to  pliancy. 

The  development  of  colloids  must  have  been  as  important 
in  the  building  of  life  as  were  the  organic  compounds.  Even 
early  in  the  earth's  growth  the  organic  compounds  must 
have  tended  toward  colloid  rather  than  crystalline  direction. 
Within  limits,  the  colloid  was  more  stable.  Crystalloids  were 
subject  to  dissolution;  in  solution,  they  contribute  to  the 
upbuilding  of  colloid  capsules. 

Conceive  of  several  units  or  globules  of  colloidal  proto- 
plasm wrapped  up  in  an  envelope,  and  we  have  a  bacterium. 
Add  more  protoplasm,  rearrange  the  internal  mechanism,  and 
we  have  a  plant  cell.  Increase  the  complexity  of  the  internal 
mechanism,  add  more  colloid  globules,  and  we  have  an 
ameba.  Give  it  a  definite  outer  garment,  and  we  have  such 
cells  as  we  are  made  of. 

A  true  cell  diff'ers  from  a  bacterium  in  its  greater  com- 
plexity of  structure  and  more  stable  dynamic  process ;  it  lives 
faster  because  it  is  better  organized  to  take  in  what  it  needs 
and  get  rid  of  the  husks.  The  animal  cell  has  greater  flexi- 
bility than  the  plant  cell;  it  can  travel  as  well  as  grow. 
It  can  live  faster,  spend  more,  and  sleep  less.    Both  diff"er 



from  a  crystal  in  having  a  larger  number  of  substances  for 
chemical  activities  to  organize. 

While  the  shape  of  living  beings  and  crystals,  says  Loeb, 
is  primarily  determined  by  the  chemical  nature  of  their 
material,  their  mechanism  of  growth  is  different.  Crystals 
grow,  and  even  restore  their  old  form  when  mutilated;  but 
only  in  "supersaturated  undercooled  solutions  of  the  mole- 
cules of  which  they  are  composed.  Living  cells  grow  in 
solutions  of  low  concentrations  of  simpler  compounds  tlian 
those  of  which  their  cells  are  composed."  They  grow  because 
they  synthesize  large  insoluble  molecules  from  comparatively 
small  soluble  molecules.  The  crystal  cannot  organize  in 
colloid  form ;  it  has  no  such  substratum  for  dynamic  changes. 

The  nature  of  the  earliest  form  of  life  we  may  never 
know.  Of  living  organisms,  bacteria  are  presumably  the 
lowest,  simplest,  and  most  primitive.  Sulphur  bacteria  obtain 
their  energy  by  the  oxidation  of  sulphuretted  hydrogen  to 
sulphuric  acid;  with  that  energy  they  fix  nitrogen  of  the 
air  and  synthesize  carbon  compounds.  We  may  speak  of 
their  energy  as  a  bioelectric  current;  their  growth,  as  electro- 
synthesis.  They  deal  direct  with  inorganic  matter.  They  are 
a  link  in  organic  evolution.  Whatever  life  is,  they  had  it. 
They  made  more  complex  bodies  possible:   lowest  plants. 

The  microscopic  one-celled  algae,  through  their  green 
chlorophyl,  began  to  store  energy  from  sunlight.  For  this 
they  needed  only  a  cell  membrane;  inside  which  they  fell 
"asleep  in  immobility." 

The  next  step  was  the  lowest  animal,  an  organism  so 
complex  that  it  got  its  energy  from  plants.  It  was  a  new 
kind  of  power  plant.  But  it  had  to  go  after  the  energy  it 
put  to  work;  the  plant  comes  to  the  animal  only  as  borne  by 
the  wind  or  water. 

Animal  and  plant  evolution  forked — one  went  one  way, 
the  other  another.  But  animals  had  to  know  which  way 
the  plants  went. 

The  first  lesson  animals  had  to  learn  was,  "Keep  moving." 



The  key  to  their  evolution  is  their  specialized  ways  to  find 
food  and  go  to  it,  and  to  know  and  to  avoid  their  enemies. 
Plants,  on  the  other  hand,  were  enjoined  to  keep  their  place 
in  the  sun.  The  green  leaf  is  the  key  to  their  evolution; 
their  interest  in  locomotion  is  chiefly  confined  to  their  seeds: 
these  must  meet  their  mates  and  be  carried  to  suitable  soil. 

The  primitive  animal  cell  had  the  world  before  it  and 
could  go  where  it  liked,  always  provided  it  never  ceased  to 
function.  It  had  to  keep  in  touch  with  a  commissary  depart- 
ment.  Life,  as  well  as  armies,  travels  on  its  belly. 

Some  dug  in,  as  the  Sporozoa;  some  went  in  for  speed,  as 
the  lively  Infusoria ;  some  just  dragged  around,  as  the  ameba 
does.  And  these  three  types  of  primitive  organisms  are 
represented  to-day  by  the  encysted,  ciliated,  and  ameboid 
cells  of  our  body. 

Where  the  single-cell  animals  began  to  combine  and  pool 
their  interests,  the  tree  of  life  took  on  new  capacities  for 
growth.  The  sky  was  the  limit — and  the  bee  beat  the  lark 
to  it. 

Both  bee  and  lark  are  animated  and  have  vital  energy. 
And  that  is  all  there  is  to  Animism  and  Vitalism. 

An  ameba  engulfs  a  diatom  and  casts  out  the  shell.  A 
drop  of  chloroform  suspended  in  water  engulfs  a  shellac- 
coated  spicule  of  glass  and  casts  out  the  spicule.  Known 
laws  of  physics  and  chemistry  suffice  to  describe  both  actions. 
But  neither  action  can  yet  be  fully  described  because  not 
all  is  known  of  the  energies  involved  in  the  two  actions. 
More  is  known  about  the  mechanism  in  which  energy  is 
manifested  in  the  drop  of  chloroform  than  in  the  blob  of 
protoplasm.  It  is  known  that  the  ameba  is  activated  by 
forces  from  without,  as  is  the  drop  of  chloroform;  not  much 
is  yet  known  of  the  mechanism  of  the  ameba  by  which  it 
makes  its  response.  The  energies  which  move  it  are  vital 
only  because  complex  mechanisms,  such  as  amebae  and  otlier 
living  protoplasm,  possess  what  is  known  as  vitality,  life. 
The  rays  which  blister  paint  and  my  skin,  dry  up  amebae, 



and  impel  green  leaves  to  synthesize  carbon  compounds,  come 
from  the  same  sun.  These  rays  are  forms  of  energy:  they 
do  things.  They  animate  nature.  When  we  stop  eating  that 
stored  energy,  we  lose  our  stored  vitality  and  soon  become 

The  chemist  can  synthesize  many  organic  molecules;  he 
cannot  yet  synthesize  a  living  protein  molecule — he  does  not 
know  its  exact  composition  and  architecture.  If  he  could 
synthesize  a  living  protein  molecule,  he  could  probably 
synthesize  protoplasm  and  build  a  living  cell.  If  he  could 
build  a  living  cell,  there  is  no  telling  what  he  might  not  do, 
for,  as  Millikan  says,  when  nature's  inner  workings  are  once 
laid  bare,  man  finds  a  way  to  put  his  brains  inside  the 
machine  and  drive  it  whither  he  will. 

In  other  words,  we  shall  know  how  life  evolved  when  we 
can  evolve  life.  That  day  will  probably  come;  it  is  yet  a 
long  way  off. 

Facts  of  evolution,  yes;  by  the  million.  Museums, 
libraries,  and  laboratories  full  of  facts.  But  no  one  law 
yet  propounded  begins  to  fit  all  the  facts.  Two  hypotheses 
have  become  famous  and  have  passed  into  current  literature ; 
they  have  given  rise  to  world-wide  controversy.  They  did 
not  describe  evolution ;  they  did  serve  mightily  to  open  men's 
minds  to  new  views  of  life  and  wider  conceptions  of  nature. 
Lamarck  and  Darwin  will  remain  great  names  in  the  history 
of  the  science  to  which  they  gave  their  lives,  but  which  was 
to  develop  into  a  real  science  of  life  only  within  the  last 
few  decades. 


A  fundamental  criterion  of  life  is  growth.  The  outstand- 
ing phenomena  of  life  are  universality  and  prodigality.  The 
only  line  life  knows  is  the  food  line.  Nature  seems  to 
abhor  a  lifeless  vacuum.  Life  abounds  in  deep  seas,  in  hot 
springs,  in  ice-cold  caves,  on  the  eternal  ice  of  glaciers. 
There  are  fish  that  climb  trees,  spiders  that  live  under  water. 



In  a  three-by-four-inch  garden  patch  Darwin  found  twenty 
kinds  of  flowering  plants.  There  are  seven  thousand  million 
diatoms  in  a  square  yard  of  pond  water.  One  Alpine  glacier 
supports  fifty  million  wingless  insects  of  a  single  species. 
In  one  bucket  of  water  there  may  be  five  million  phos- 
phorescent microorganisms.  A  ship  may  plow  through  count- 
less millions  of  billions  of  them  for  hours.  In  a  pinch  of 
soil  there  may  be  twenty  billion  colloidal  food  particles 
supporting  a  hundred  million  bacteria,  fourteen  million  fungi 
and  algae,  and  five  thousand  protozoa. 

Life  is  a  spendthrift  breeder.  Elephants  are  the  slowest, 
yet  Darwin  calculated  that  one  pair  in  750  years  would 
have  19,000,000  descendants.  Australia  has  often  told  the 
world  what  one  pair  of  rabbits  can  do.  Fish  are  worse. 
A  cod  can  lay  6,000,000  eggs;  a  ling,  28,000,000.  Even 
the  ling  would  be  crowded  out  of  the  sea  if  just  one  oyster 
were  let  alone  by  all  and  sundry  until  it  had  great-great- 
grandchildren. If  all  survived.  Lull  says,  there  would 
be  just  66,000,000,000,000,000,000,000,000,000,000,000 
oysters.  Their  shells  would  make  a  pile  eight  times  the 
size  of  the  earth! 

Oysters  only  produce  60,000,000  eggs  a  year.  A  starfish 
produces  over  200,000,000.  But  even  a  starfish's  progeny 
are  but  a  drop  in  the  bucket  compared  with  the  yield  of 
one — not  a  pair,  just  one — Paramecium.  This  animal,  just 
visible  to  the  naked  eye,  has  been  domesticated  in  a  Yale 
laboratory  by  Woodruff.  He  studied  its  capacity  to  occupy 
the  whole  known  universe:  not  our  puny  solar  system,  the 
universe.  At  the  end  of  the  9,000th  generation  there  would 
not  be  room  for  a  star  or  a  comet  or  a  nebula  in  the  sky. 
The  universe  would  be  solid  Paramecium. 

But  the  universe  is  not  solid  Paramecium,  nor  have  there 
ever  been  19,000,000  elephants  at  large  at  any  one  time, 
nor  can  we  travel  from  New  York  to  Southampton  on  a  road- 
bed of  oyster  shells.  Why  not?  Because,  in  short,  life  is 
a  fight.    Which  survive? 



Here  is  where  Darwin  got  his  key  to  evolution.  Nature 
herself  decides;  she  selects.   Natural  Selection. 

But,  does  not  like  beget  like?  Are  we  not  all  created  free 
and  equal?  Darwin  knew  better;  as  does  every  farmer. 
Animals  breed  true;  but  they  vary.  Peas  in  a  pod  vary. 
Rabbits  of  a  litter  vary.  Identical  twins  vary.  Without 
variation,  there  could  be  no  evolution.  Variation  is  the 
law  of  the  universe.  Living  beings  vary,  the  environment 
varies.  There  is  overproduction,  and  a  struggle  for  existence. 
In  that  struggle  the  fittest  would  survive.  Harmful  variations 
would  be  eliminated,  beneficial  characters  intensified  and 
modified;  characters  neither  hurtful  nor  beneficial  would 
persist  through  heredity.  Man  himself  carries  around  two 
hundred  characters  he  could  dispense  with,  but  which  are 
not  so  unfit  that  nature  weeds  them  out. 

There  followed  much  talk  of  "survival"  values  and  of 
"adaptations."  One  marsupial  "survives"  because  it  is  a 
jumper;  another,  because  it  is  a  sprinter;  another,  because 
it  is  a  climber.  One  snake  survives  by  turning  a  tooth  into 
a  hypodermic  syringe,  his  saliva  into  venom;  another  keeps 
his  teeth,  but  changes  his  skin  to  look  like  that  of  his  poi- 
sonous brother;  another  parts  with  teeth  entirely,  and  devel- 
ops a  spine  in  his  gullet  to  break  birds'  eggs.  He  is  "adapted" 
for  climbing. 

Remove  the  "adaptations"  from  a  whale,  there  is  nothing 
left.  Some  whales  have  big  teeth  in  big  jaws  and  a  gullet 
big  enough  for  a  Jonah.  Their  equally  big  cousins  have 
no  teeth  and  a  gullet  so  small  they  must  strain  their  food 
through  a  whalebone  sieve.  They  are  "right"  because  the 
right  kind  to  yield  lots  of  blubber  and  whalebone. 

Milton's  whale,  that  "at  his  gills  draws  in,  and  at  his  trunk 
spouts  out,  a  sea,"  would  be  an  "adaptation"!  Especially 
if  its  young  were  born  alive  and  took  nourishment  from 
mammary  glands,  as  all  whales  do.  Whales  have  no  "gills," 
no  "trunk."   They  are  perfectly  good  mammals,  as  mammal 



as  bat,  giraffe,  or  man.  Why  did  they  go  back  on  their 
country  and  go  in  for  aquatics?  Why  are  some  whales  as 
gentle  as  turtledoves,  others  as  mean  as  sharks?  Wliy  are 
there  Negritos  and  Nordics?  Natural  selection  must  work 
overtime  to  answer  these  questions. 

What  kind  of  variation  may  we  expect  to  find  in  a  land- 
lubber that  takes  to  water  and  adapts  one  branch  of  its  family 
to  fight  sharks  and  another  branch  to  live  on  nothing  that 
would  not  pass  through  a  finger  ring?  Did  you  ever  try 
to  catch  food  in  your  mouth  and  swallow  it,  fifty  feet  under 
water?  Any  whale  can.  The  first  whale  that  tried  that  trick 
drowned:  it  transmitted  nothing,  not  even  a  taste  for  salt 
water.  Think  of  the  "adaptations"  a  whale  had  to  part 
with  to  become  adapted  to  water. 

De  Vries,  a  Dutch  botanist,  suggested  the  mutation  theory 
as  a  way  out.  Life  does  not  always  vary  by  slight  change, 
but  sometimes  by  jumps.  Breeders  call  them  "sports." 
Perhaps  the  first  tailless  ape  was  a  sport.  Perhaps  man 
himself  is. 

But  can  the  "sport"  hand  on  the  essence  of  its  change? 
For  example,  a  human  sport  with  four  toes  can  found  no 
four-toed  dynasty  unless  the  four-toedness  is  a  transmissible 
trait.  Again,  the  trait  which  characterizes  the  sport  may 
have  no  "survival"  value;  it  may  even  prove  a  handicap  in 
the  struggle  for  existence.  In  either  case,  it  will  lead  to  no 
permanent  change.  It  is  difficult  to  see  how  the  mutation 
theory  can  work,  apart  from  natural  selection. 

Some  variations  are  "predetermined":  they  are  inherent 
in  the  developing  egg.  Or  they  may  be  "acquired"  after 
birth,  called  out  by  outside  influence.  They  may  be  "chance" 
variations,  subject  to  no  known  law;  such  are  the  variations 
"selected"  according  to  the  Darwinian  law.  Or  they  may 
be  "orthogenetic,"  as  Osborn  calls  them:  they  seem  to  point 
in  some  definite  direction.  Most  variations  are  "continuous" 
and  of  slight  quantity:  these  also  enter  into  the  Darwinian 



calculation.  Or  they  may  be  "discontinuous":  of  large 
quantity,  the  "mutants"  of  De  Vries.  Some  books  on  evolu- 
tion abound  in  such  jargon.  It  gets  us  no  nearer  to  the 
cause  of  variation. 

After  the  first  shock,  people  began  to  like  Darwin  and 
his  fittest  doctrine.  "Survival  of  the  Fittest!  Aren't  we 
here?  We  are  the  fittest!  Darwin  says  so."  Many  0.  K.'d 
Darwin  without  knowing  that  merely  to  be  alive  under  domes- 
tication is  no  proof  of  fitness,  mental,  moral,  or  physical. 
When  they  realized  that  they  could  not  count  on  Darwin  for 
a  Personal  Fitness  certificate,  they  lost  interest  in  evolution 
and  blamed  Darwin  for  having  taken  them  in.  And 
grounded  their  blame  on  the  monstrous  proposition  that 
Darwin  sought  to  drive  God  from  the  world! 

Darwin  himself  would  have  been  the  last  soul  in  the  world 
to  do  such  a  thing.  He  had  no  wish  to  disturb  anyone's 
religious  beliefs.  On  the  contrary,  knowing  that  the  pub- 
lication of  his  findings  would  challenge  the  Mosaic  cos- 
mogony, he  held  back  for  twenty  years  and  did  not  publish 
until  he  was  actually  anticipated  by  Wallace.  And  then  he 
said  he  felt  like  a  murderer!  But  no  scientist  ever  less 
deserved  the  reproach  of  the  Church.  Nor  does  it  become 
the  physicist,  L.  T.  More,  even  in  "trying  to  vindicate  the 
belief  in  our  spiritual  nature,"  to  bear  false  witness  against 
Darwin,  as  he  does  in  his  Dogma  of  Evolution,  just  issued 
by  the  Princeton  University  Press.  Darwin  died  as  he  had 
lived,  a  Christian  gentleman. 

Darwin  did  not  discover  evolution,  but  he  so  presented 
the  facts  of  and  the  case  for  evolution  that  the  world  believed. 
In  the  fact  that  Darwin  and  Lincoln  had  a  common  birthday 
(February  12,  1809),  Lull  sees  Darwin  as  an  "emancipator 
of  human  minds  from  the  shackles  of  slavery  to  tradition," 
as  Lincoln  was  the  "emancipator  of  human  bodies  from  a 
no  more  real  physical  bondage."  His  nobleness  of  character 
and  generosity  of  disposition  were  not  less  than  Lincoln's. 




"All  that  has  been  acquired  or  altered  in  the  organization 
of  individuals  during  their  life  is  preserved  by  generation 
and  transmitted  to  new  individuals  which  proceed  from  those 
which  have  undergone  change,"  said  Lamarck,  a  great  French 
naturalist  who  died  nearly  one  hundred  years  ago,  blind,  in 
poverty,  a  social  outcast — for  telling  the  truth  as  he  saw 
it!  He  coined  the  word  "biology";  it  thrives.  Biologists 
have  driven  a  hundred  daggers  into  his  theory  of  evolution 
through  the  Inheritance  of  Acquired  Characters;  the  theory 
is  as  alive  as  ever! 

To  find  out  if  "acquired  characters"  could  be  inherited, 
thousands  of  animals  were  mutilated;  Weismann  himself  cut 
off  mice's  tails  for  twenty-two  generations!  They  gave  it  up, 
realizing,  as  Conklin  puts  it,  that  wooden  legs  are  not  inher- 
ited, but  wooden  heads  may  be. 

I  may  "acquire"  such  development  of  the  muscles  of  my 
breast  and  abdomen  that  I  can  dance  the  "hootchy-kootchy"; 
that  is  one  thing.  To  have  those  muscles  cut  out  is  something 
else,  certainly  not  an  "acquired"  trait.  The  marvel  is  that 
Weismann's  silly  experiment  ever  got  into  print  as  experi- 
mental "evidence"  that  there  is  nothing  to  Lamarck's  theory 
of  evolution. 

"Every  animal  climbs  up  its  own  genealogical  tree,"  says 
Thomson.  But  that  no  more  disproves  Lamarck's  theory 
than  Weismann's  mice  that  were  born  with  tails.  If  an 
animal  never  takes  the  first  step,  it  can  never  take  the  second. 
Nothing  added  to  zero  gets  nowhere;  adding  more  zeros  adds 
nothing;  nor  climbs  any  genealogical  tree.  Something  gets 
added.  Otherwise  nature  could  not  have  made  a  man  out  of 
a  monkey  or  a  mammal  out  of  a  reptile. 

Novelties  do  get  into  life.  Spinal  column,  prehensile  tail, 
blue  eyes,  were  once  novelties.  There  was  a  time  when  there 
was  no  such  thing  as  spine,  tail,  or  eye,  in  any  living  being. 
To  say,  as  Davenport  seems  to,  that  they  are  not  really 



inherited  but  persist  because  parent  and  offspring  are  "chips 
from  the  same  old  block,"  is  to  make  the  same  "old  block" 
a  Pandora's  box. 

Man's  arm,  bat's  wing,  horse's  leg,  whale's  flipper,  bird's 
wing,  and  turtle's  paddle,  all  evolved  from  the  fin  of  a  fish. 
These  are  typical  "adaptations";  they  are  characters  which 
have  been  acquired;  whether  "inherited"  or  not,  they  are 

But  they  cannot  be  transmitted,  said  Weismann,  because 
the  germ-plasm  is  sacred,  immortal,  and  continuous;  nothing 
can  get  at  it,  nothing  can  touch  it.  Tennyson's  immortal 
brook  had  nothing  on  Weismann's  germ-plasm.  But  that 
brook  does  become  a  river;  and  somehow,  some  way,  a  piece 
of  the  original  life-germ,  or  germs,  has  come  to  be  a  human 

Biologically,  immortality  is  a  figure  of  speech,  but  based 
on  certain  facts,  namely:  all  living  things  grow,  and  if  they 
cannot  grow  young  they  grow  old  and  die.  Whatever 
"immortality"  is,  then,  it  involves  the  process  of  either 
remaining  young  or  of  growing  young,  "rejuvenescence." 
Later,  we  shall  see  how  man  and  higher  animals  renew  their 

Weismann's  doctrine  of  the  "continuity  of  the  germ- 
plasm"  held  sway  for  three  decades,  and  still  furnishes  texts 
for  well-meaning  enthusiasts  who  have  a  case  to  prove.  It 
is  an  especially  useful  ingredient  in  eugenic  and  political 
pies.  But  as  we  shall  see,  there  is  nothing  sacred  about  the 
germ-plasm,  nor  is  it  alone  allowed  an  immortal  heritage. 
Body  cells  also  are  potentially  immortal.  "Immortality" — 
for  germ-cells,  for  soma  cells,  for  all  living  organisms — is 
contingent  upon  an  inherited  mechanism  and  upon  physical 
and  chemical  conditions  of  environment. 

The  old  formulae  do  not  suffice  to  explain  the  facts  of 
evolution.  The  facts  have  outgrown  the  old  theories.  Evolu- 
tion is  up  and  down,  back  and  forth;  a  circulating,  pulsating, 
inextricably  woven  web. 



We  see  life  in  fragments.  Fragments,  individuals,  arise 
by  fission  or  reproduction  from  pre-existing  individuals. 
Each  individual  must  be  "adapted"  to  get  food  and  oxygen. 
Each  individual  strives  to  occupy  the  earth — as  does  oxygen 
or  hydrogen;  in  this  it  adapts  itself  to  diverse  conditions, 
or  it  dies.  Evolution  proceeded  not  on  one  but  on  several 
lines.  The  main  lines  led  to  food  and  oxygen,  self -protection, 

There  are  two  great  problems:  how  have  individuals 
become  adapted  to  the  conditions  in  which  we  find  them? 
Natural  Selection  seems  to  have  been  the  limiting  factor. 
How  have  their  organs  become  adapted  to  the  functions  they 
perform?  The  Inheritance  of  Acquired  Characters  seems  to 
have  been  the  decisive  factor. 

The  great  problem  Darwin  tried  to  solve  was  the  origin 
of  species.  There  are  species.  Man  is  a  species.  The 
gorilla  is  a  species.  How  species  arose  is,  after  all,  only 
the  problem  of  inheritance,  of  heredity,  of  individual  varia- 
tion, writ  large.  The  more  this  problem  is  examined,  the 
less  simple  it  seems.  It  is  far  from  solved.  Segregation  is 
an  important  factor;  inbreeding  tends  to  swamp  variation. 

Probably  no  one  law  can  be  formulated  which  will  ade- 
quately describe  the  processes  of  evolution.  It  is  obvious 
that  if  an  animal  is  not  fit  to  survive  it  will  perish,  and  that 
if  there  were  no  variations  there  would  be  no  evolution. 
Selection  does  work  on  variations — in  nature  as  in  Wall 
Street;  but  as  time  goes  on  we  shall  probably  hear  less  and 
less  of  selection,  variation,  adaptation,  etc.,  and  more  and 
more  of  the  nature  of  the  physico-chemical  mechanism  which 
exhibits  living  behavior  under  livable  conditions.  Under 
such  conditions  living  things  do  certain  tilings,  show  a  certain 
capacity  for  a  certain  range  of  behavior.  One  of  the  striking 
features  of  that  range  of  behavior  is  the  power  to  grow.  In 
fact,  nothing  so  characterizes  livingness  as  its  capacity  for 
reproduction.  This  is  so  great  in  lower  animals  that  they 
are  conceived  of  as  endowed  with  immortality.   With  higher 



animals  "immortality"  becomes  a  special  affair  of  the  so- 
called  germ-cells. 


The  very  lowest  organisms  have  nothing  comparable  to 
sex.  Woodruff's  one-celled  paramecium  is  in  its  10,000th 
generation.  If  each  generation  equaled  man's,  his  original 
Paramecium  would  now  be  well  over  a  quarter  of  a  million 
years  old.  Yet  it  remains  eternally  young  and  shows  no  loss 
of  virility.  As  fast  as  one  paramecium  tires  of  existence  it 
renews  its  youth  by  becoming  two,  "which  go  on  playing 
the  fascinating  game  of  living  here  and  now." 

Some  protozoa  show  the  beginnings  of  sex.  Two  indi- 
viduals unite  (conjugate)  to  become  one;  nuclear  material 
is  exchanged  and  divided:  one  becomes  two  again  and  these 
two  grow  and  divide.  Conjugation  is  evidently  a  rejuvenation 
process.  Other  protozoa  only  partially  unite — and  again 
separate,  "rejuvenated."  In  other  species,  a  small  individual 
bores  into  and  buries  its  body  within  that  of  a  normal-sized 
individual;  the  latter  then  divides  repeatedly. 

Thus  far  there  is  no  division  of  labor  or  true  sex  forms. 
When  two  unite  the  conjugation  is  an  energy  stimulus,  as 
though  the  spring  of  life  needed  rewinding.  In  higher  organ- 
isms, this  rewinding  becomes  the  prime  function  of  the 

In  volvox,  a  high  protozoon,  thousands  of  cells  held 
together  by  protoplasmic  threads  unite  into  a  colony.  When 
the  colony  is  full-grown,  certain  cells  become  engorged  with 
food  and  are  of  great  size.  These  big  cells  now  divide  into 
many  small  cells,  break  away  from  the  parent  colony,  and 
form  a  little  colony  of  their  own,  where  they  grow  to  full 

But  in  some  volvox  colonies,  certain  cells  may  divide  and 
form  bundles  of  cells  of  rod-like  bodies  with  whip-lash  tails. 
One  of  these  now  conjugates  with  a  cell  of  the  other  type; 



this  then  divides  and  founds  a  new  colony.  The  cells  of 
the  colony  which  were  not  concerned  in  reproduction  live 
awhile  longer,  and  die. 

Natural  death  had  appeared.  Also  germ-cells:  egg-cells; 
sperm-cells.  The  idea  of  male  and  female  began  with  a 
volvox  colony  of  protozoa. 

The  egg-cells  of  the  volvox  colony  were  large;  the  sperm- 
cells,  minute.  This  disproportion  in  size  holds  good  for  the 
entire  animal  kingdom.  The  mammal  spermatozoon  may  be 
only  l/100,000th  part  as  large  as  the  barely- visible-to-the- 
naked-eye  ovum. 

One  volvox  colony  may  produce  both  ova  and  sperma,  or 
only  ova,  or  only  sperma.  The  volvox,  therefore,  is  either 
unisexual  or  hermaphroditic — it  is  neither  male  nor  female. 
As  the  ova  themselves  can  form  complete  colonies  witliout 
the  need  of  fertilization,  the  volvox  is  also  parthenogenetic 
(virgin-reproduction).  In  short,  volvox,  as  Geddes  says,  is 
an  "epitome  of  the  evolution  of  sex." 

Many  lower  metazoa  are  so  small  that  only  with  the 
microscope  can  males  be  distinguished  from  females.  There 
is  no  mating,  no  sex  complex.  Ova  and  sperma  are  turned 
loose  to  find  each  other  as  best  they  may;  for  every  ovum 
there  are  tens  of  thousands  of  sperma. 

Higher  in  the  scale,  sex  distinctions  tend  to  be  more  pro- 
nounced, but  the  evolution  of  sex  forms  does  not  follow  a 
straight  line.  Sometimes  the  sexual  differences  are  unnotice- 
ably  slight;  sometimes  they  reach  absurd  and  amazing  forms. 
The  difference  between  certain  spider  males  and  females  is 
equivalent  to  a  man  of  normal  size  married  to  an  eighty-foot- 
high  woman  weighing  a  hundred  tons.  The  female  of  one 
species  of  worms  is  a  hundred  times  larger  than  the  male; 
he  lives  in  her  oviduct  as  a  parasite. 

Difference  between  the  two  sexes  is  most  conspicuous  in 
birds.  But  in  rooks,  kingfishers,  and  some  parrots,  there 
are  no  secondary  sex  characters.  Even  many  mammals  show 
none  or  almost  none:  mice,  rabbits,  cats.    In  vertebrates  as 



a  whole,  conspicuous  sexual  differences  are  the  exception; 
in  the  entire  animal  kingdom  similarity  is  the  rule. 

Now  from  this  brief  resume  of  the  history  of  sex  let  us  see 
what  is  back  of  it.  Are  sex  and  fertilization  primary  attri- 
butes of  life? 

After  years  of  study  Woodruff  concludes  that  "the  proto- 
plasm of  a  single  cell  may  be  self-sufficient  to  reproduce 
itself  indefinitely,  under  favorable  environmental  conditions, 
without  recourse  to  conjugation."  In  other  words,  the  union 
of  two  cells,  or  two  organisms,  is  not  the  essential  element 
of  new  cells  or  organisms.  Proper  environment  alone  is 
enough  to  enable  the  paramecium  to  reorganize  its  nucleus 
and  continue  dividing  indefinitely. 

More  suggestive  is  the  behavior  of  simple  planarian  flat- 
worms,  studied  for  years  by  Child  with  interesting  results. 
Life  processes  in  planaria  are  naturally  highest  at  the  head 
and  diminish  toward  the  tail.  Cut  one  into  three  pieces:  the 
head  part  grows  a  tail,  the  tail  grows  a  head.  Normally, 
a  head  will  grow  at  the  end  of  the  middle  piece  which  was 
toward  the  head,  a  tail  at  the  other  end.  But  Child  can 
reverse  this!  He  can  so  alter  the  life  process  that  a  head 
will  grow  out  from  the  tail  end,  a  tail  from  the  head  end. 
The  net  result  is  the  same:  from  one  old  worm,  three  new 
worms.  With  no  more  "conjugation"  or  "fertilization"  than 
a  scalpel. 

What  happens  when  the  professor  is  not  looking?  At  the 
end  of  the  season  the  old  planaria  break  into  bits.  In  the 
spring,  each  bit  grows  into  a  new  worm. 

"Germ-cells"  are  not  unlike  these  bits  of  worms;  they 
are  not  young  but  old  cells.  They  become  young  by  union. 
In  other  words,  the  whole  theory  of  the  need  of  sexed  parents 
for  carrying  on  the  spark  of  life  breaks  up  with  planaria. 
Even  the  theory  of  the  need  of  special  germ-cells  to  carry 
on,  falls  flat.  Any  group  of  planarian  body-cells  is  the 
potential  bearer  of  immortality. 



Loeb  "fertilized"  a  frog's  egg  with  a  hatpin.  Delage  had 
already  found  that  starfish  and  other  marine  metazoa  could 
get  along  without  fathers.  Eggs  could  not  only  be  fertilized 
with  various  chemicals,  but  the  developing  embryos  could 
be  turned  this  way  or  that,  or  checked  in  growth  at  different 
stages,  or  be  made  to  assume  monstrous  forms,  or  become 
twins.  With  tannin  and  ammonia  he  not  only  "fertilized" 
starfish  eggs,  but  grew  one  with  six  rays — nature  allows  them 
but  five. 

Among  mammals,  fertilization  of  ova  from  one  species  by 
sperms  from  a  closely  allied  species  occurs.  The  hybrid 
mule  is  sterile,  but  the  hybrid  offspring  of  a  bull  and  a 
buffalo  is  fertile.  In  lower  vertebrates,  and  especially  among 
invertebrates,  there  are  innumerable  cases,  according  to  Mar- 
shall, where  the  sperms  of  one  species  can  fertilize  the  ova 
of  other  species. 

Riddle's  ringdove  that  laid  eleven  eggs  and  then  began 
to  behave  like  a  male,  and  was  found,  after  an  autopsy,  to 
have  lost  her  ovaries  through  tuberculosis  and  to  have  devel- 
oped male  sex-glands  instead,  seems  to  indicate  that  neither 
structure  nor  behavior  has  a  fixed  and  uncontrollable  basis 
in  heredity.  The  germ-cell  chromosomes,  or  whatever  it  is 
that  makes  for  hereditary  characters,  can  be  modified  and 
even  reversed. 

For  example,  food  may  cause  great  change  in  structure. 
Tadpoles  fed  on  thymus  gland  become  big,  dark  tadpoles — 
but  never  develop  into  frogs;  if  fed  adrenal  gland,  they 
become  very  light  in  color.  Larvae  of  bees  fed  royal  jelly 
become  queens;  on  bee  bread,  unfertile  females  or  workers. 
Canaries  fed  on  sweet  red  pepper  become  red  in  color.  The 
germ  as  the  "bearer  of  heredity"  is  meaningless  or  monstrous 
apart  from  its  usual  environment. 

The  egg  is  the  parent  of  the  chicken,  and  of  more  eggs. 
What  these  eggs  will  develop  into  depends  on  many  hitherto 
unsuspected  factors;  as  yet  almost  beyond  control  because 



so  little  known.  But  among  these  factors  is  physical  and 
chemical  environment. 

A  male  element,  as  represented  either  by  one  of  two 
similar  conjugating  cells  or  by  a  distinctive  sperm  which 
"fertilizes,"  is  not  a  necessary  factor  in  the  reproduction  of 
life.  But  in  truly  bisexual  animals  fertilization  is  a  life- 
saving  act,  as  Loeb  calls  it;  if  the  germs  are  not  fertilized, 
they  die.  Fertilization  also  seems  to  be  essential  for 
biparental  inheritance. 

No  father,  no  inheritance  from  the  father's  side.  Bisexual 
reproduction  made  variation  possible.  Variation  is  newness. 
Newness  began  with  life  when  life  was  one-celled.  That  one 
cell  was  both  germ  and  body  cell  combined.  It  gradually 
surrendered  its  functions  to  daughter  cells.  Some  developed 
capacities  to  high  degrees;  they  are  fit  only  for  detailed, 
specialized  work.  Some  remained  close  to  the  primitive 
original  form.  Groups  of  such  primitive  cells  can  renew 
their  vigor  and  begin  anew. 

But  in  the  complex  mechanisms  of  higher  vertebrates,  the 
function  of  propagation  came  to  be  reserved  for  certain 
cells.  At  the  same  time  the  struggle  for  life  became  keener. 
The  male  element  was  a  useful  mechanism  for  novelties:  it 
doubled  the  chance  for  variation,  it  made  it  possible  for  the 
organism  to  acquire  something  new.  If  the  something  new 
was  harmful,  nature  "selected"  it  for  death. 

The  first  business  of  sex,  then,  was  to  put  new  energy 
into  life,  to  release  life,  to  keep  it  young  and  flowing.  Sex 
thus  appears  as  one  of  the  many  adaptations  whereby  living 
beings  could  become  more  highly  organized  and  so  carry  on 
on  a  higher  scale.  The  development  of  special  organs  for 
reproduction  is  comparable  to  the  development  of  special 
organs  for  digestion,  for  respiration,  etc.  It  was  not  until 
evolution  was  well  advanced  that  the  sperm  or  male  element 
assumed  a  share  in  the  burden  of  heredity.  This  assumption 
was  a  great  step  in  the  evolution  of  higher  organisms. 




A  fragment  cut  from  a  single-celled  animal  can  move,  but 
cannot  grow  unless  it  contains  part  of  the  nucleus  of  the 
animal.  Every  living  cell  (except  red  blood-cells)  of  every 
living  body,  and  every  body  of  one  cell,  has  a  dense  central 
part,  called  a  nucleus.  No  one  knows  just  what  the  nucleus 
is,  but  it  is  the  essential  part  of  all  cells.  A  one-thirtieth 
part  of  a  sea-urchin's  egg  will  live,  grow,  and  develop  into 
a  complete  sea-urchin,  if  that  thirtieth  part  contains  a  portion 
of  the  nucleus.  That  thirtieth  part  of  an  egg  is  germ-plasm. 
Any  protoplasm  is  germ-plasm  if  it  can  grow  a  new 

Ordinarily,  cells  divide  by  what  is  known  as  direct 
division — a  constriction  appears  at  the  middle  of  the  cell, 
increasing  until  finally  the  cell  separates  into  two  distinct 
cells.  But  in  fertilized  ova,  the  division  is  indirect  or  mitotic 

As  the  nucleus  seems  to  be  the  vital  spot  of  the  germ,  and 
as  a  certain  part  of  it  stains  beautifully  and  so  looms  up 
under  the  microscope,  it  is  called  chromatin  (colored  stuff). 
No  germ-cell  divides  until  this  chromatin  performs.  At  first 
a  mere  network,  the  chromatin  becomes  a  long,  continuous, 
tangled  skein.  Then  it  breaks  into  bits,  or  units,  called 
chromosomes  (colored  bodies) ;  they  are  always  the  same  in 
each  species  and  vary  in  number  from  two  to  several  hun- 
dreds— six  in  mosquitoes,  sixteen  in  rats,  twenty-four  in 
mice,  forty-eight  in  man,  etc.  Further,  these  units  assume 
definite  shapes  in  different  species,  and  are  always  in  pairs. 

Just  outside  the  nucleus  is  a  small  granule  called  the 
centrosome.  While  the  chromatin  is  taking  its  definite  thread 
shape,  the  centrosome  divides  into  two,  which  migrate  to 
opposite  sides  of  the  ovum.  Meanwhile,  the  nuclear  wall 
disappears  and  its  fluid  mingles  freely  with  the  surrounding 
protoplasm.  From  each  centrosome  spindles  radiate  out 
toward  the  center  of  the  cell.   At  this  equator  and  to  the  ends 



of  the  spindles  the  chromosomes  now  arrange  themselves; 
and  divide — each  chromosome  splits  lengthwise  and  becomes 
two!  The  two  sets  of  chromosomes  now  begin  to  withdraw 
from  each  other  toward  the  centrosomes. 

Meanwhile,  the  round  ovum  begins  to  lengthen,  then  begins 
to  constrict  at  the  equator.  The  chromosomes  begin  to 
increase  in  size  until  each  becomes  as  big  as  the  parent 
chromosome.  The  spindle  fibers  disappear.  A  wall  begins 
to  form  around  the  chromosomes.  The  cell's  equator  has 
grown,  smaller;  it  is  an  hour-glass  form.  It  breaks  in  two. 
The  one  ovum  has  become  two  cells.  The  chromosomes 
again  become  mere  chromatin,  vaguely  seen  in  the  dense 
mass  of  the  nucleus,  for  the  surrounding  wall  is  now 

What  was  one  is  now  two,  each  complete:  blob  of  proto- 
plasm, nucleus,  everything.  The  most  wonderful  thing  in 
the  world.  It  is  potentially  a  full-grown  animal,  complete 
unto  itself.    All  it  needs  is  food  and  safety. 

That  is  the  way  we  grew  up:  one  cell  became  two,  two 
became  four,  four  .  .  . 

The  oocytes  from  which  ova  develop,  and  the  spermato- 
gonia which  become  sperms,  are  present  at  the  time  of  birth. 
Although  they  are  among  the  last  of  the  cells  of  the  body  lo 
mature,  they  are  set  aside  early  in  embryonic  development. 
The  big  difference  between  sperm  and  ovum  is  size  and 
behavior.  The  ovum  has  much  protoplasm  and  no  means 
of  locomotion.  The  sperm  is  all  nucleus — except  its  long 
tail  of  cytoplasm,  as  protoplasm  outside  the  nucleus  is  called. 
By  this  whip-lash  tail  it  travels. 

Before  the  parent  sperm  and  ovum  unite,  they  go  through 
a  maturation  or  ripening  process  vv^hereby  the  number  of 
chromosomes  in  each  germ-cell  is  cut  in  two.  The  fertilized 
human  ovum  thus  starts  with  the  original  number  of  chromo- 
somes— forty-eight,  half  being  contributed  by  each  parent 
germ-cell.  The  maturation  process  is  in  general  like  that 
of  ordinary  division  by  mitosis.   But  the  chromosomes  unite 



in  pairs;  thus,  one  of  each  paired  unit  passes  to  each  cell 
formed  by  the  division. 

During  fertilization  the  head  and  "middle  piece''  of  the 
sperm  enter  the  ovum,  the  head  being  equivalent  to  the 
divided  nucleus  of  an  ordinary  cell  in  process  of  mitosis. 
The  middle  piece  becomes  the  centrosome — in  maturing,  the 
ovum  lost  its  own  centrosome.  It  is  this  new  centrosome  that 
divides  as  above  described,  each  new  body  taking  position 
as  in  ordinary  mitosis.  The  chromatin  of  the  two  nuclei 
now  splits  into  chromosomes,  etc.  What  was  a  fertilized 
ovum  is  two  cells.  The  development  of  a  rat,  an  elephant, 
or  a  human  being,  has  begun. 

The  fertilized  human  ovum  has  forty-eight  chromosomes, 
twenty-four  from  each  parent  germ.  Here  is  where  heredity 
is  supposed  to  get  in  its  work,  and  Mendel's  law  is  supposed 
to  preside  over  the  cutting  of  the  inheritance. 


We  all  inherit  something,  if  only  crooked  legs  or  a 
tendency  to  twins.  And  we  all  have  ancestors:  in  fact,  a 
surprising  number  if  they  had  not  intermarried.  Reckoning 
three  generations  to  a  century,  each  of  us  to-day  is  entitled 
to  120,000,000,000,000  lineal  ancestors  in  A.  D.  1.  They 
intermarried.  At  no  time  has  this  earth  seen  120,000,000,000 
people,  much  less  120,000,000,000,000.  Kaiser  Wilhelm 
had  162  ancestors  ten  generations  ago — ^he  was  entitled  to 
512.   All  Anglo-Saxons  are  at  least  thirtieth  cousins. 

We  have  ancestors.  We  inherit  features,  traits,  characters, 
peculiarities — marks  of  individuality  whereby  each  of  us  is 
not  only  a  separate  entity,  but  different  in  detail  from  every 
other  individual  on  earth. 

How  do  we  get  these  traits?  What  traits  are  heritable, 
what  are  not?  The  game  of  heredity  was  evolved  to  answer 
these  questions.  The  game  presupposes  a  knowledge  of 
germ-cell  division,  a  speaking  acquaintance  with  chromo- 



somes,  the  assumption  that  they  are  made  up  of  countless 
distinct  and  definite  chromomeres,  and  faith  in  two  theories — 
germ-plasm,  eternal  and  inviolable;  chromomeres,  the  "ulti- 
mate" bearers  of  heredity.  Thomson  recommends  also  two 
ordinary  packs  of  playing  cards  from  which  the  kings  have 
been  removed.  Why  kings  is  not  explained.  Each  is  now 
a  short  deck — forty-eight  cards.  How  many  chromosomes  in 
the  human  body?  Forty-eight. 

We  inherit  twenty-four  maternal  and  twenty-four  paternal 
chromosomes:  possible  permutations,  16,777,216.  That  is 
nothing.  That  only  refers  to  possible  permutations  for  one 
single  specific  pair  of  individual  germs.  Counting  potential 
germ  capacity  for  the  life  of  one  pair  of  parents  gives  us 
the  tidy  range  of  total  possible  different  combinations  in  all 
the  fertilizable  ova  as  300,000,000,000,000. 

Now  imagine  that  we  deal  not  with  a  mere  forty-eight- 
chromosome  permutation  system,  but  with  forty-eight  chromo- 
somes each  consisting  of  "countless"  chromomeres,  each  a 
possible  bearer  of  heredity!  In  that  case,  as  Thomson  says, 
every  human  germ-cell  would  be  "absolutely  unique"— and 
undoubtedly  is. 

Some  biologists  play  this  game  because  they  feel  impelled 
to  have  a  frame  on  which  they  can  hang  heredity.  They  are 
not  agreed  as  to  what  heredity  is.  But  there  are  the  "colored 
bodies."  They  do  not  know  what  they  are.  All  right.  Hang 
heredity  on  them.  Solve  the  mystery  by  multiplying  it  by 
forty-eight  unknowns. 

What  is  heredity?  Heredity  is  germ-plasm.  How  does 
heredity  work?  By  the  beads  on  the  thread  of  chromatin. 
Maybe.  Maybe  heredity  counts  its  beads:  one  bead  for 
each  generation.  The  question  is:  does  this  hypothesis  get 
us  farther  into  life  than  Darwin's  "gemmules"  or  Weismann's 
"biophores"?  I  do  not  see  that  it  does.  It  does  seem  to 
get  us  in  deeper. 

Now  for  the  "traits."  Are  you  a  female?  It  is  a  "Men- 
delian"  trait.    Are  you  bald-headed?    See  Mendel.  Are 



your  fingers  all  thumbs?  "Mendelian"  dominance.  Daven- 
port, specialist  in  heredity,  no  longer  finds  anything  mys- 
terious in  the  sudden  appearance  of  atavistic  characters.  We 
are  full  of  such  "grandpa"  characters:  they  are  "latent"; 
they  appear  according  to  Mendel's  law  of  heredity.  Mendel 
would  be  surprised  if  he  could  come  back! 

Gregor  Mendel  was  a  monk,  lived  in  a  cloister,  taught 
school,  and  had  a  hobby — ^garden  peas.  He  died  in  1884 
at  the  age  of  sixty-two,  and  was  promptly  forgotten.  Wliat 
he  found  out  about  peas  and  buried  in  a  little  article  in 
1866  was  not  discovered  until  1900 — the  world  had  been 
too  busy  with  Darwin.  What  this  discovery  started  is  still 
going.  Mendel  is  less  abused  to-day  than  Darwin;  some 
think  he  made  a  greater  discovery.    He  certainly  is  a  cult. 

Walter  thus  formulates  Mendel's  "law":  "When  parents 
that  are  unlike  with  respect  to  any  character  are  crossed, 
the  progeny  of  the  first  generation  will  be  like  the  dominant 
parent  with  respect  to  the  character  in  question.  When  the 
hybrid  offspring  of  this  first  generation  are  crossed  with 
each  other,  they  will  produce  a  mixed  progeny:  25  per  cent 
will  be  like  the  dominant  grandparent;  25  per  cent  like  the 
other  grandparent;  50  per  cent  like  the  parents  resembling 
the  dominant  grandparent." 

And  plenty  of  stufi"ed  mice  and  guinea-pig  martyrs-to- 
science  in  museum  cases  prove  that  Mendel's  law  works.  It 
stands  on  three  legs: 

1.  Independent  unit  characters.  While  we  inherit  a  gen- 
eral plan  of  structure,  we  inherit  details,  or  traits,  as  "inde- 
pendent units." 

2.  Dominance.  Brown  eyes  marry  blue:  offspring  all 
brown-eyed.  Brown  is  a  positive  character,  dominant;  blue 
is  negative,  "recessive."  By  the  fact  of  its  dominance,  brown 
appears.  The  blue  may  be  present  in  the  germ-plasm,  but 
as  long  as  the  "determiner"  is  also  present,  blue  will  be 
unable  to  show  itself.  "Unit"  characters  are  inlierited 
through  "determiners"  in  the  germ-plasm. 



3.  Segregation,  or  purity  of  the  germ-cells.  A  sperm  cell 
or  an  ovum  can  have  only  one  of  two  "alternating  char- 
acters." For  example,  either  blue-eyed  or  brown,  but  not 
both.  Cross  a  blue-eyed  with  a  brown-eyed:  the  fertilized 
ovum  will  contain  both  blue  and  brown  units;  the  offspring 
will  be  brown-eyed;  brown  is  the  determiner.  But  half  this 
offspring's  germ-cells  will  possess  the  blue-eyed  unit;  half, 
the  brown-eyed;  no  one  germ-cell  will  have  both.  The  "alter- 
nating" characters  will  have  been  segregated. 

This  segregation  of  alternate  characters  was  Mendel's  chief 
point.  The  way  the  chromosomes  divide  in  the  maturing 
germ-cell  seemed  a  good  machine  to  try  it  on.  Investigators 
began  to  count  chromosomes,  and  on  each  hang  a  "unit" 
character.  As  there  were  more  "units"  than  chromosomes, 
they  postulated  chromomeres.  As  these  could  not  be  seen 
and  so  checked  up,  they  could  postulate  as  many  as  they 

But  experiments  show  much  conflict,  nor  are  experimenters 
agreed  as  to  results  or  general  conclusions.  They  can  rarely 
know,  if  ever,  whether  the  stock  is  "pure,"  a  hybrid,  or  a 
blend.  New  "Mendelian"  factors  have  been  added:  "com- 
plementary," "supplementary,"  "inhibitory,"  "cumulative," 
"lethal."  "Units"  may  be  "independent"  as  to  quality  or 
as  to  quantity;  or  a  unit  may  function  by  being  "absent"! 
A  "dominant"  character  that  performed  true  to  form  for 
three  generations  practically  gave  up  in  the  seventh  genera- 
tion ;  showing  a  discrepancy  between  man's  and  nature's  idea 
of  "dominance."  There  seems  often  no  real  stability  in  the 
parent  type.  On  cross-mating  it  breaks  down ;  the  component 
characters  recombine  into  different  or  new  types. 

If  man  bred  as  fast  as  mice  and  guinea-pigs,  we  should 
know  more  about  our  own  Mendelian  "units"  than  we  do 
now.  Enough  is  known,  however,  to  support  a  Eugenics 
Society.  Its  motto  is:  When  in  doubt,  marry  a  dissimilar; 
you  may  thereby  skip  a  generation  with  a  wooden  head. 




Can  we  control  our  own  evolution?  Do  we  want  to?  To 
what  end?  In  which  direction?  Presumably  we  could;  and 
this  is  as  far  as  eugenics  has  any  standing  in  a  court  of 
science.  All  the  rest  of  eugenics  is  politics — based  on 
assumptions  open  to  opposite  views  or  on  race  prejudice  pure 
and  simple. 

Man  could  probably  breed  a  race  of  human  beings  with 
the  following  "traits":  bald,  fat,  long  chest,  short  and 
crooked  legs,  left-handed,  six-fingered  and  all  fingers  thumbs 
and  webbed,  near-sighted,  deaf  and  dumb,  feeble-minded, 
curly  haired,  cataract,  albino,  long-lived,  and  prolific,  with 
a  tendency  to  twins;  at  any  rate,  these  are  a  few  of  the  many 
so-called  Mendelian  traits  capable  of  transmission.  There 
are  said  to  be  at  least  thirty-four  different  hereditary  eye 
defects  alone,  eight  of  which  can  produce  blindness. 

With  nothing  more  to  work  with  than  normal  variation  in 
wild  rock  pigeons,  man  has  bred  over  twenty  races  of  pigeons. 
What  could  he  not  do  with  the  human  race  if  ...  !  The 
"if"  introduces  politics.  And  to  "breed"  a  race  of  humans 
involves  a  decision  as  to  what  is  desirable;  a  thousand-year- 
long dynasty  of  cast-iron  despots  with  such  power  over  sub- 
jects as  Herod  never  hoped  for  or  breeder  of  slaves  dared 

What  are  we  to  breed  at?  What  is  the  new  race  to  go  in 
for?  Stature,  tow  hair,  blue  eyes,  eight  fingers,  toothless,  one 
toe,  fecundity,  mental  precocity?  The  list  of  heritable  traits 
is  indefinite.  "Marry  dissimilars"  is  probably  good  eugenic 
advice  if  we  are  not  bent  on  handing  down  our  own  personal 
traits — but  most  people  are  satisfied  with  their  traits.  At 
any  rate,  the  sex  impulse  itself  generally  chooses  its  mate, 
and  that  impulse  is  not  primarily  concerned  in  offspring. 

Take  stature.  If  height  is  the  criterion  for  desirable  citi- 
zens, early-and-often  marriage  should  be  encouraged  in  Iowa, 
Kentucky,  and  Missouri;  made  late  and  rare  in  New  York, 



Pennsylvania,  and  Massachusetts;  and  prohibited  in  Rhode 
Island.  Meanwhile,  close  Ellis  Island  to  all  but  native  Pata- 

What  shall  we  do  with  the  Attic  Greeks?  Raise  their 
"quota,"  or  exclude  them  because  they  do.  not  look  like  the 
Harvard  graduate  who  fathers  an  average  of  only  three- 
fourths  of  a  son  and  the  Vassar  graduate  who  mothers  one- 
half  of  a  daughter? 

If  there  is  anything  in  the  "continuity  of  the  germ-plasm" 
theory,  there  should  be  some  good  germs  left  in  a  country 
which  in  150  years  produced  such  statesmen  as  Miltiades, 
Themistocles,  Aristides,  and  Pericles;  such  poets  as  Aes- 
chylus, Euripides,  and  Sophocles;  such  scientists  as  Socrates, 
Plato,  and  Aristotle;  such  artists  as  Phidias  and  Praxiteles; 
such  historians  as  Thucydides  and  Xenophon ;  such  orators  as 
Aeschines,  Demosthenes,  and  Lysias.  The  whole  earth,  in  no 
centuries  before  or  since,  declared  Galton,  produced  such  a 
galaxy  of  illustrious  men. 

Some  of  that  germ-plasm  may  be  blacking  boots  to-day 
on  a  Staten  Island  ferry  or  running  a  short-order  restaurant 
in  El  Reno.  Who  knows?  One  thing  is  certain:  if  it  is,  it 
is  more  interested  in  a  short  shine  or  a  long  order  than  it 
is  in  eugenics. 

Could  anyone,  even  Francis  Galton  himself,  from  the  hill 
behind  Athens  in  the  year  600  B.  c,  have  predicted  that  within 
a  hundred  years  the  little  Rhode-Island-sized  state  of  Attica 
would  begin  to  bud  genius  so  fast  and  so  big  that  the  world 
has  not  stopped  wondering  about  it  yet? 

Could  Galton  have  predicted  Lincoln?  Could  Ellis  Island? 
Can  Ellis  Island  spot  the  Jukes  from  the  Altmans,  or  have  the 
faintest  idea  when  it  holds  up  a  Steinmetz — or  an  Edward 

The  Jukes  case  is  notorious — and  illuminating,  and  was 
thoroughly  investigated  by  Davenport.  The  case  began  about 
150  years  ago  with  a  lazy,  mentally  defective  "Max"  who 
settled  not  far  from  New  York  City.    His  two  sons  married 



into  a  family  of  six  sisters,  all  harlots.  One  of  them  was 
known  as  "Margaret,  the  mother  of  criminals." 

Of  the  2,094  progeny  of  the  Jukes  sisters,  1,258  were  liv- 
ing in  1915:  65  were  "good  citizens";  600  were  feeble- 
minded and  epileptic.  "Criminal,"  "harlot,"  "mentally  de- 
fective," "drunkard,"  "pauper,"  recur  in  their  records  again 
and  again;  now  and  then,  "murderer."  In  seventy-five  years 
alone,  Max's  feeble-minded  pauper  progeny  cost  New  York 
State  a  million  and  a  quarter  of  dollars. 

Looks  like  a  plain  case — segregation  or  a  surgeon.  And 
yet  a  Jukes's  descendant  may  be  a  governor  and  several  of 
them  may  be  in  Congress.  Some  say  they  are.  Conceivably, 
a  Jukes  might  become  a  second  Pasteur — and  save  more  lives 
than  were  lost  in  the  World  War.  This  is  certain:  the  state 
or  nation  which  permits  marriage  between  mental  defectives 
and  deaf  mutes  will  have  to  provide  for  deaf  mutes  and 
feeble-minded.  We  may  improve  the  breed  of  figs  and  eradi- 
cate thistles,  but  never  will  we  gather  figs  from  thistles  or 
good  figs  from  poor  fig  stock. 

What  carries  eugenics  into  politics  is  that  the  Jukes  are 
neither  figs  nor  thistles,  and  we  do  not  yet  know  just  how 
feeble  a  mind  has  to  be  before  it  has  to  be  locked  up  to  pro- 
tect those  who  have  minds  and  refuse  to  use  them. 

Many  Jukes  have  too  much  brain  to  be  segregated,  not 
enough  to  carry  a  rifle  to  the  front.  Selection.  That  kind 
of  selection  is  a  modern  specialty.  The  sound-minded  able- 
bodied  get  shot,  the  priests  and  scholars  will  not  marry,  and 
the  ambitious  women  and  the  selfish  men  transmit  their 
names  but  not  their  germs. 

Is  civilization  now  breeding  a  "pure"  Andy  Gump  type — 
no  teeth,  no  lower  jaw?  Cigarettes  may  save  the  lower  lip, 
and  chewing  gum  may  save  enough  of  the  lower  jaw  to  sup- 
port a  chewing  gum.  But  a  full  and  sound  set  of  teeth  these 
days  is  about  as  primitive  as  is  a  perforated  olecranon  fossa 
of  the  humerus. 

Natural  selection  is  always  at  work.    In  every  million 



births,  not  counting  stillborns,  there  are  2,687  deaths  the 
first  year  from  congenital  malformation.  A  certain  other 
small  percentage  who  can  never  be  happy  or  useful,  are 
nursed  along  for  a  varying  number  of  years.  This  fraction 
is  undoubtedly  larger  in  civilized  than  in  natural  conditions; 
it  is  probably  increasing.  It  offers  a  social  and  biologic 
problem.  That  problem  is  not  likely  to  be  solved  in  the  near 
future  because  we  have  too  many  abstract  formula?  about 
humanity  and  too  little  common  sense  for  solving  concrete 
social  problems. 

But  the  "racial  purity"  and  the  "racial  inferiority"  behind 
such  books  as  McDougall's  Is  America  Safe  for  Democracy? 
Chamberlain's  Foundations  of  Nineteenth  Century  Civiliza' 
tion;  Grant's  The  Passing  of  the  Great  Race;  Wiggam's  The 
New  Decalogue  of  Science;  Gould's  America  a  Family 
Matter;  and  East's  Mankind  at  the  Crossroads,  are  bunk  pure 
and  simple.  If  these  United  States  wish  to  restrict  immigra- 
tion to  "Nordics"  or  to  this  or  that  political  group,  why  not 
say  so  and  be  done  with  it?  To  bolster  up  racial  prejudice 
or  a  Nordic  or  a  Puritan  complex  by  false  and  misleading 
inferences  drawn  from  "intelligence  tests"  or  from  pseudo- 
biology  and  ethnology,  is  to  throw  away  science  and  fall  back 
on  the  mentality  of  primitive  savagery. 

Evolution  produced  a  human  brain,  our  only  remarkable 
inheritance.  Nothing  else  counts.  Body  is  simply  brain's 
servant.  Treat  the  body  right,  of  course;  no  brain  can  func- 
tion well  without  good  service.  But  why  worry  more  about 
the  looks,  color,  and  clothes  of  the  servant  than  the  service  it 




J.  Life  Is  Change  and  Requires  Energy.  2.  The  Body  Is  a  Living  Machine. 
3.  It  Requires  Calories.  4.  Why  We  Must  Digest  Food.  5.  The  Digestive 
System.  6.  Our  Daily  Bread  and  Water.  7,  Seeing  Food  Through  the  Canal. 
S.  How  Food  is  Absorbed.  9.  The  Flesh  Is  in  the  Blood.  10.  How  the 
"Flesh"  Is  Transported.  11.  Giving  the  Blood  the  Air.  12.  The  Great  Blood 
Purifier.  13.  The  Red  Blood-Cells.  14.  The  Body  Thermostat.  15.  The  Role 
of  the  Duct  Glands.   16.  The  "Little  Fleas."   17.  The  Deadly  Germs. 


All  change  implies  resistance  overcome,  work  done,  en- 
ergy. Energy  is  ability  to  work.  Without  energy  there  is 
no  work  done  or  change  in  any  living  being.  Change  in  liv- 
ing beings  takes  many  forms.  Growth,  maintenance,  repair, 
regulation,  secretion,  chemical  synthesis,  muscular  activity, 
contraction  and  relaxation,  heat  production — all  these  are 
changes,  living  processes.    They  require  energy. 

Energy  required  for  engines  is  stored  in  fuel — organic 
compounds  such  as  coal,  wood,  oil,  etc.  Energy  used  for 
life  processes  is  also  stored  in  fuel — organic  compounds  fed 
into  the  body  as  sugars  and  fats.  Most  of  our  food  is  physio- 
logical fuel.  This  fuel  is  "burned"  in  the  body,  releasing 
energy.  This  burning  is  called  oxidation.  Our  vitality  can 
be  measured  by  the  rate  of  oxidation.  When  oxidation  ceases, 
animation  ceases.  Even  individual  cells  die  when  deprived 
of  oxygen.  In  dividing  cells  the  rate  of  oxidation  is  speeded 

Oxidation  is  a  chemical  change  and  takes  place  only  under 
certain  conditions,  temperature,  etc.  During  oxidation  heat 
is  released,  as  it  is  every  time  we  bat  an  eye,  lift  a  finger,  or 



think;  batting  an  eye,  lifting  a  finger,  and  thinking  are  forms 
of  work,  energy-consuming  processes. 

What  is  oxidation?  It  can  be  seen  in  a  furnace;  it  has 
never  been  seen  in  a  living  organism.  But  during  oxidation 
something  becomes  something  else,  presumably  by  means  of 
an  ion  or  carrier  of  a  charge  of  electricity;  something  in- 
creases its  electrical  charge;  the  electrical  charge  of  some- 
thing else  decreases;  oxygen  unites  with  something  else,  form- 
ing an  oxide.  We  constantly  exhale  carbon  dioxide — the  end- 
product  of  the  oxidation  of  carbon.  Heat  is  always  liberated 
during  oxidation;  our  exhaled  air  is  always  warm  air. 

Our  viscera  consume  much  energy  in  capturing  oxygen  and 
in  converting  foods  into  physiological  fuel,  especially  into 
a  sugar  called  glucose,  or  when  stored  in  the  liver,  muscles, 
or  other  tissues,  called  glycogen.  Stimulate  the  splanchnic 
nerve  with  electricity,  and  the  liver  will  convert  glycogen  to 
glucose — by  hydrolysis;  rearrange  the  molecules  of  glucose, 
it  becomes  lactic  acid,  which  by  dehydrogenation  becomes 
pyruvic  acid.  This,  oxidized,  becomes  acetaldehyde.  This, 
oxidized,  becomes  carbon  dioxide  and  water — materials  to 
be  eliminated  from  the  body  that  plants  may  reincorporate 
them  into  sugar-cane  or  grapes  or  potatoes. 

When  man  digs  up  the  potato,  the  "potato"  that  is  in  his 
arm  as  glycogen  is  oxidized,  but  only  partially.  The  fate 
of  the  lactic  acid  that  is  left  over  is  not  quite  known,  but 
oxidation  processes  are  known  to  be  involved. 

What  is  oxidation,  then?  Every  process  involved  in  digging 
up  potatoes  or  in  thinking  about  potatoes.  Potatoes  them- 
selves are  stored  energy.  Cut  one  open;  it  turns  black — • 
that  also  is  oxidation. 

A  helping  of  mashed  potatoes  contains  enough  energy  to 
raise  the  temperature  of  about  400  pounds  of  water  about 
two  degrees,  or  to  enable  a  man  to  sweat  enough  to  keep  his 
body  cool  for  one  hour's  work  digging  potatoes. 

The  potatoes  carried  to  the  cellar  will  lie  dormant,  if  the 
cellar  is  not  too  warm  and  damp,  until  the  following  spring. 



Then,  cut  into  bits  and  put  into  warm,  moist  ground,  they 
will  begin  to  grow.  Each  "eye"  of  each  potato  will  grow; 
it  is  a  "germ."  Every  living  germ,  whether  plant  or  animal, 
contains  enough  stored  energy  to  enable  it  to  respond  to 
vital  situations.  In  its  responses  or  actions  it  will  capture 
more  energy.  The  capacity  of  growing  things  for  work  is 
perhaps  the  most  astounding  phenomenon  in  the  universe. 
Growing  trees  can  split  rocks  with  their  roots  and  lift  tons  of 
matter  hundreds  of  feet  above  the  ground.  Swelling  peas  in 
an  iron  pot  lifted  a  cover  weighted  with  160  pounds. 

Now  here  is  a  curious  thing.  The  potato  digger  dies  when 
his  heart  stops  beating.  He  is  dead;  but  millions  and  millions 
of  cells  of  his  dead  body  will  remain  alive  for  hours — they 
have  not  yet  exhausted  their  oxygen  and  fuel.  Aseptically 
removed  from  the  body  and  kept  moist  on  ice,  some  tissue 
cells  will  remain  alive  for  ten  days.  If  placed  in  a  certain 
solution  and  oxygen,  their  life  can  be  prolonged  indefinitely. 
Connective  tissue  cells  have  been  cultivated  for  years.  All 
they  seem  to  require  is  proper  environment.  Their  capacity 
to  live  and  multiply  outside  man's  body  has  opened  new 
conceptions  of  life. 

Life  is  a  dynamic  relationship  between  structure  and  en- 
vironment. We  do  not  live  long  when  the  oxygen  of  our 
environment  is  shut  off.  The  faster  we  live,  the  more  oxygen 
we  require.  When  our  reptilian  ancestor  improved  the 
mechanism  begun  by  amphibia  for  capturing  oxygen  from 
the  air  instead  of  from  the  water,  an  enormously  important 
step  in  life  was  made.  When  our  mammalian  ancestor,  by 
supplying  a  diaphragm,  perfected  that  mechanism,  breathing 
became  a  delight  and  oxygen  easy  to  get.  Fast  living  became 
possible.  But  whether  we  live  fast  or  slow,  and  whether  we 
work  with  our  hands  or  with  our  brains,  or  do  no  work  at 
all,  our  living  body  must  work  to  keep  alive.  We  must  have 
energy.  We  cannot  get  it  from  an  electric  current,  we  can- 
not get  it  from  mere  gravity,  we  cannot  get  it  from  the  rays 
of  the  sun  as  plants  can,  but  get  it  we  must  or  die.    As  our 



bodily  mechanism  and  all  animal  bodies  are  internal-com- 
bustion engines,  we  get  our  energy  from  the  oxidation  of 
foodstuffs  converted  into  physiological  fuel.  The  capture 
and  transformation  of  energy  is  the  most  fundamental  of  all 
living  processes.  How  food  and  oxygen  are  made  available 
for  consumption  in  our  growing-going  bodily  mechanism  is 
a  process  of  fundamental  importance. 


When  we  finish  our  day's  work,  we  walk  to  our  car  and 
drive  home.  (We  may  have  no  car:  we  allow  ourselves  one 
for  purposes  of  illustration.) 

The  motor-mechanism  with  which  we  walk  to  our  car 
weighs  about  eighty  pounds :  sixty  of  muscle,  twenty  of  bones. 
With  every  step  we  take,  about  300  muscles  are  in  action. 
Only  as  muscles  contract  and  relax  can  we  move.  By  con- 
tracting, muscles  shorten — they  do  not  push,  they  pull.  The 
bones  support  the  muscles,  the  muscles  move  the  bones  as 

Muscles  are  in  opposing  groups.  With  a  certain  group  we 
turn  our  head;  mere  relaxing  of  this  group  will  not  restore 
the  head  to  its  original  position:  we  must  use  the  other  group. 
To  balance  our  head  on  our  spine,  we  use  20  muscles;  to 
balance  our  spine  with  each  step,  144  muscles. 

Muscles  are  engines,  each  made  up  of  hundreds  of  thou- 
sands of  tiny  individual  muscle-cell  engines.  With  each  step, 
over  one  hundred  million  engines  are  at  work. 

When  muscle  responds  to  stimulus  of  nerve  or  electrode 
of  an  induction  coil,  lactic  and  perhaps  some  other  acid 
is  liberated  from  some  compound  in  the  muscle  itself.  This 
reaction  changes  the  hydrogen  ion  concentration  in  the  muscle 
cell;  it  contracts,  shortens.  Some  of  the  lactic  acid  is  oxi- 
dized and  heat  is  formed,  the  remaining  lactic  acid  is  re- 
stored to  the  compound  from  which  it  was  used.  Meanwhile, 
the  glycogen  stored  in  the  muscle  has  been  called  on  to  supply 



the  energy  of  the  transaction.  With  the  disappearance  of  the 
lactic  acid,  the  muscle  returns  to  its  former  resting  condition; 
it  relaxes.  All  this  takes  place  in  all  the  half -million  or 
more  muscle  cells  of  every  single  muscle  involved. 

Microscopically  small  blood  vessels  bring  oxygen  and 
fuel  which  is  "burned"  with  the  aid  of  oxygen,  without 
which  there  is  no  combustion  in  muscle  or  auto  engine.  Micro- 
scopically small  veins  carry  away  the  products  of  combus- 
tion, the  same  in  muscle  as  in  the  auto  engine — ^water  and 
carbon  dioxide.  In  the  kidneys  the  blood  is  relieved  of  the 
water;  in  the  lungs,  of  the  carbon  dioxide. 

The  blood  itself  is  driven  about  by  the  heart,  an  engine  of 
such  tiny  muscle  engines  so  fused  together  that  they  cannot 
be  teased  apart  with  the  finest  needle.  Marvelous  it  is  that 
the  heart  knows  how  fast  it  must  do  its  work  if  it  is  to  give 
adequate  service.  While  quiet  at  our  desk,  the  heart  pours 
about  five  pints  of  blood  into  our  aorta  every  minute.  Wlien 
we  run  uphill,  the  heart  will  drive  blood  into  the  aorta  seven 
times  that  fast — thirty-five  pints  a  minute!  And  from  the 
great  aorta  the  blood  will  be  carried  to  every  one  of  the 
millions  of  millions  of  cells  in  the  body.  Wherever  the  body 
is  scratched,  wherever  the  mosquito  dips  his  bill,  there  blood 
is  found. 

Running  uphill  requires  much  energy:  much  sugar  is  oxi- 
dized, much  carbon  dioxide  is  generated.  Hence  the  faster 
heartbeat,  to  hurry  the  blood  to  get  more  oxygen  and  fuel, 
to  get  rid  of  more  carbon  dioxide.  The  extra  sugar  needed 
is  picked  up  from  the  sugar-bin  in  the  liver;  the  oxygen  is 
got  from  the  lungs.  While  the  red  blood-cells  are  reloading 
oxygen  from  the  six  million  air-sacs  in  the  lungs,  the  blood 
itself  is  giving  up  its  excess  carbon  dioxide. 

These  air-sacs  are  always  ready  to  do  their  duty.  That  is 
why  the  bellows  moved  by  twenty-four  levers  of  bone  must 
work  faster  in  uphill  work;  they  must  keep  the  air  in  the 
lung  air-sacs  constant;  not  have  more  than  5  per  cent  of 
carbon  dioxide.    But  as  running  uphill  burned  up  seven 



times  as  much  fuel  as  sitting  at  rest,  there  was  seven  times 
as  much  waste  product  of  combustion  to  be  got  rid  of.  That 
makes  us  "pant":  our  bellows  work  faster  and  keep  up  the 
pace  until  the  normal  proportion  of  carbon  dioxide  is  re- 
stored in  the  little  air-sacs. 

We  need  about  thirty  ounces  of  fuel  a  day  to  keep  our 
body  machine  in  good  trim.  The  combustion  of  that  fuel 
makes  just  the  same  amount  of  heat  in  our  body  engines  as  if 
burned  in  any  other  engine.  In  fact,  so  much  of  our  fuel 
goes  into  heat  that  if  we  could  not  get  rid  of  the  surplus  gen- 
erated in  running  or  in  any  hard  work,  our  blood  would 

One  ameba  has  been  seen  to  chase  another  ameba,  catch 
up  with  it,  begin  to  swallow  it,  lose  it,  chase  it  again,  recap- 
ture it,  lose  it,  chase  it,  capture  it,  and  "swallow"  it:  by  flow- 
ing around  it  and  thus  inclosing  it  within  its  own  body.  By 
and  by  the  little  cannibal  opened  up  its  body  and  moved  away 
from  the  debris  of  the  dead  ameba.  A  little  later  it  divided 
and  then  there  were  two.  (Few  of  us  can  do  more  than 
that  in  a  day — some  do  less  in  a  lifetime  and  leave  nothing 
behind  but  the  debris  of  their  dead  protoplasm.)  That  ameba 
has  no  liver,  no  alimentary  canal,  heart,  lungs,  gills,  or 
mouth.  Yet  in  that  little  body  of  one  cell  every  essential 
phenomenon  of  life  takes  place.  It  functions,  even  as  a 
human  being. 

The  difference  between  ameoa  and  man  is  not  unlike  that 
between  a  tiny  motor-boat  and  the  biggest  ship  afloat.  Man 
has  more  parts,  the  parts  are  vastly  more  intricate.  He  carries 
a  heavier  load,  moves  faster,  goes  farther. 

All  this  requires  great  energy.  But  we  no  more  make 
energy  than  a  motor  or  a  dynamo.  We  must  capture  it  first, 
then  convert  it.  Every  move  we  make,  every  word  we  speak, 
every  thought  that  passes  through  our  brain,  every  beat  of 
our  heart,  every  breath  we  draw  awake  or  asleep,  requires 
energy;  and  all  the  while  we  must  run  a  refrigerating  plant 
or  boil  over,  and  a  heating  plant  or  freeze  to  death.  Our 



motor  mechanism  must  be  oiled  at  every  point  of  friction. 
Our  nervous  system  must  be  protected,  cleaned,  and  kept  in 
repair.  Because  we  are  fearfully  and  wonderfully  made,  we 
must  have  much  energy  merely  to  keep  alive. 

But  as  long  as  we  are  alive,  and  whether  afoot  or  on 
horseback,  awake  or  asleep,  we  are  going  machines:  the 
chest  rises  and  falls,  the  heart  beats,  the  blood  circulates, 
metabolism  goes  on,  life  functions;  energy  is  required.  But 
however  energetic  we  may  feel,  we  cannot  will  our  heart  to 
stop  beating  or  commit  suicide  by  holding  our  breath;  we 
may  hold  our  breath  long  enough  to  lose  consciousness:  our 
lungs  then  will  resume  rising  and  falling.  Back  of  conscious 
effort,  and  so  well  organized  that  conscious  effort  may  be 
dispensed  with,  is  a  human  body  which  functions  as  long  as 
it  is  fed  and  can  maintain  itself  in  a  state  of  dynamic  equilib- 

Our  inheritance  seems  to  have  set  a  limit  to  the  duration 
of  that  equilibrium.  To  discover  its  nature  and  how  to  main- 
tain it  is  the  great  problem.  Now  that  we  have  ceased  to 
be  merely  objects  of  religious  superstition  or  of  philosophic 
speculation,  we  can  take  our  lease  on  life  into  a  court  where 
it  can  have  a  fair  trial.  That  court  has  already  solved  great 
problems  formerly  held  in  awe  and  garbed  in  mystery.  There 
is  no  known  inherent  reason  why  the  problem  of  dynamic 
equilibrium  in  living  organisms  should  not  be  solved. 

The  ameba  solved  it;  man  solves  it  for  fragments  (the 
germ-cells)  of  his  body.  Even  tumor  cells  are  potentially 
immortal.  Much,  if  not  all,  of  the  tissue  of  our  body  is 
potentially  tumor.    If  ameba  solved  it,  why  not  man? 

The  goal  is  such  knowledge  of  the  living  that  disease  may 
be  prevented  and  the  grave  robbed  of  its  victory.  W^e  of  this 
generation  shall  not  attain  that  goal,  but  it  is  a  goal  toward 
which  humanity  may  turn  with  much  hope  and  some  confi- 
dence. Meanwhile,  there  is  the  immediate  problem  of  hang- 
ing on  to  such  lease  of  life  as  has  been  bequeathed  to  us. 
As  a  nation  with  unlimited  resources  and  as  a  race  with  large 



brains,  we  abuse  our  lease  of  life,  often  with  fatal  results. 
Many  preserve  their  strength  merely  to  make  their  lungs 
breathe  and  their  heart  beat.  The  evolution  that  ended  with 
reptiles  sufficed  for  such  processes;  human  brains  were 
evolved  for  higher  forms  of  life. 


You  may  be  growing:  you  require  food  to  build  up  tissue. 
You  may  be  going:  you  require  energy.  Both  growing  and 
going  are  change,  metabolism.  But  building  is  an  assimila- 
tion process;  you  construct  or  repair  something:  that  is  con- 
structive metabolism,  or  anabolism.  But  the  exhibition  of 
energy  involves  dissimilation;  by  converting  complex  sub- 
stances into  simple  ones  you  destroy  something:  that  is  de- 
structive metabolism,  or  katabolism.  In  both  metabolic  proc- 
esses there  is  a  residue:  husks  not  used  in  assimilation,  others 
left  from  the  destruction.  These  are  excretions  and  must 
be  eliminated  from  the  body. 

Our  energy  is  derived  from  fuel  in  the  form  of  food.  Our 
daily  fuel  needs  vary  according  to  our  age,  size,  sex,  and 
especially  the  amount  of  energy  we  expend.  A  lumberjack 
expends  more  energy  than  a  lounge-lizard. 

A  pound  of  sugar  burned  in  our  body  yields  as  much  heat 
as  a  pound  of  sugar  burned  in  a  chemical  oven.  Heat  is  a 
form  of  energy,  and  when  measured  in  units  required  to 
raise  the  temperature  of  one  kilogram  (about  two  pints)  of 
water  from  0°  to  1°  Centigrade  (about  2  degrees),  is  called 
a  calorie^  or  "great  calorie." 

Sugar  burned  in  our  body  makes  energy  available.  Of 
such  fuel  we  normally  have  in  reserve  and  stored  in  muscles 
and  the  liver  about  ten  ounces,  or  1,200  calories.  That  is 
potential  energy.  Suppose  we  burn  it,  as  we  do  when  chop- 
ping wood;  how  much  energy  would  we  get?  Enough  to  lift 
a  weight  of  one  hundred  tons  to  a  height  of  three  feet.  That 
is  our  normal  potential  energy  reserve. 



To  do  nothing,  just  to  keep  alive,  quiet,  flat  on  our  back,  we 
require  about  1,700  calories  a  day,  enough  to  lift  nearly 
two  hundred  tons  one  foot.  That  amount  of  energy  goes 
into  heartbeat,  breathing,  keeping  the  body  at  a  constant 
temperature  and  alive.   It  is  called  basal  metabolism. 

The  energy  consumption,  in  calories,  per  kilogram  in 
doubling  the  birth  body  weight  is:  colts,  4,512;  lambs,  4,243; 
kittens,  4,554;  babies,  28,864.  It  is  biologically  significant 
that  the  child  of  man  requires  six  times  more  energy  to 
grow  a  pound  than  a  calf  does.  And  for  every  calf  of  stunted 
growth  in  the  world  there  are  600  stunted  children!  Basal 
metabolism,  as  we  might  expect,  is  highest  in  childhood.  After 
the  fifteenth  year  it  drops  sharply  to  twenty,  thereafter  it 
slowly  declines  throughout  life.  The  growing  body  stores  up 
energy  in  the  form  of  new  tissue. 

We  eat  a  meal;  digestion  is  metabolism  also,  work.  For 
the  work  of  digesting  a  meal,  170  calories  must  be  added  to 
the  1,700  needed  for  basal  metabolism.  Reading  is  work: 
for  two  hours,  add  10  calories  more;  for  a  five-mile  walk  or 
two  hours  at  golf,  300  calories;  for  twelve  hours  swivel-chair 
work  (mostly  expended  in  muscle  work  in  holding  the  body  in 
the  chair),  250  calories.  Total,  2,450  calories;  or  say  2,500 
for  an  average  man.  In  a  body  completely  relaxed  but  with 
the  brain  actively  at  work,  so  little  extra  energy  is  consumed 
that  the  calorimeter  cannot  find  it!  The  more  active  the  work, 
the  more  calories  required.  A  farmer  will  use  up  1,000  more 
calories  a  day  than  a  bookkeeper.  A  lumberman  may  use  up 
7,000  in  one  day;  a  six-day  bicyclist,  10,000. 

Food  consumed  in  excess  of  energy  required  is  stored  as 
fat:  under  the  skin,  around  the  abdomen,  between  the  muscles; 
but  not  in  the  more  active  tissues — even  a  "fat-head"  has 
little  fat  in  his  brain. 

Du  Bois  points  out  that  when  a  man  has  maintained  a 
weight  of  165  pounds  for  twenty  years — as  many  do — it 
means  that  of  a  total  consumption  of  18,250,000  calories  he 



has  not  stored  or  lost  more  than  9,300,  enough  calories  for 
two  pounds  of  fat — "an  exactness  equaled  by  few  mechanical 
devices  and  almost  no  other  biologic  process."  But  suppose 
a  man  of  165  pounds  doubles  his  weight  in  twenty  years; 
that  means  that  he  has  added  22  pounds  of  fatty  tissue  and 
133  pounds  of  fat.  And  one  small  extra  pat  of  butter  a  day 
will  do  it;  there  is  enough  energy  in  that  pat  of  butter  to 
walk  one  and  one-third  miles.  As  Du  Bois  says,  he  ate 
eleven  grams  too  much  butter,  or  walked  one  and  one-third 
miles  too  little. 

Sitting  up  in  a  chair  is  work:  muscles  are  contracted, 
energy  is  liberated  as  heat  and  as  work  performed.  Both 
can  be  measured  in  calories,  the  work  calories  in  terms  of 
the  mechanical  equivalent  of  heat.  This  has  practical  value. 
A  machine  that  develops  three  heat  to  one  work  calorie  is 
25  per  cent  efficient.  Muscles  holding  up  the  body  in  a  chair 
develop  three  heat-calories  to  one  of  work.  Our  muscles  are 
about  25  per  cent  efficient.  But  a  trained  muscle  is  40  per 
cent  efficient.  A  habitual  chair-worker  requires  less  energy 
to  sit  still  than  does  one  accustomed  to  being  on  his  feet. 
Some  men  find  sitting  in  a  chair  for  any  length  of  time  really 
hard  work. 

Two  men  at  the  same  work,  blow  for  blow,  stroke  for 
stroke,  step  for  step :  one  sweats ;  the  other  is  cool  as  a  cucum- 
ber. One  was  not  used  to  it,  was  not  trained;  many  of  his 
calories  went  into  heat.  The  other  was  trained,  it  was  his 
steady  job;  he  got  more  work  out  of  his  calories. 

To  get  more  work  out  of  our  calories  is  to  function  better. 
To  function  better  is  to  live  longer.  If  we  find  that  the  thing 
we  trust  to  pick  the  mother  of  our  children  is  simply  a  double- 
barreled  pump,  knowledge  of  our  heart  or  the  liquid  refresh- 
ment it  pumps  to  our  brain  will  not  grow  more  nerve  cells, 
but  it  should  make  us  less  nervous  and  more  respectful  of 
the  pump  and  the  refreshment  it  delivers;  when  it  stops,  the 
brain  starves  to  death. 




Water,  carbon  dioxide,  and  nitrogen  made  life  possible. 
Bacteria  make  plants  possible.  Plants  make  animals  pos- 
sible. Did  it  ever  occur  to  you  that,  apart  from  a  few  but 
necessary  mineral  salts,  everything  we  eat  is  or  has  been 
alive?  About  50  per  cent  of  our  body  is  carbon.  We  are 
oxidizing  carbon  every  moment  of  our  life.  We  must  have 
carbon.  We  can  eat  lampblack,  charcoal,  and  diamond  dust 
(all  carbon) ;  we  cannot  digest  them.  Anything  we  eat  and 
do  not  digest  remains  a  foreign  substance  that  must  be  elimi- 
nated. There  is  carbon  dioxide  in  the  air  we  breathe,  but  we 
cannot  build  the  carbon  of  that  compound  into  our  body  or 
burn  it  for  its  energy  with  the  aid  of  the  oxygen  of  the 
water  we  drink.  In  short,  we  are  dependent  on  shoddy, 
second-hand  material.  Plants  are  closer  to  Nature  and  not 
so  dependent. 

To  photograph  is  to  light- write;  to  photo  synthesize  is  to 
light-put-together.  With  sunlight  through  a  green  filter  called 
chlorophyl  (green-leaf)  plants  decompose  the  carbon  dioxide 
of  the  air  and  combine  its  carbon  with  the  oxygen  and  hydro- 
gen of  water  to  make  carbohydrates  (carbon-water),  so  named 
because  they  always  contain  hydrogen  and  oxygen  in  the  same 
proportions  as  they  are  found  in  water — twice  as  much  hydro- 
gen as  oxygen. 

The  simplest  carbohydrate  is  sugar.  But  sugar  is  soluble 
and  easily  washed  away.  When  plants  need  to  store  sugar, 
they  change  it  to  a  starch.  Starch  is  a  more  complex  sugar, 
same  kind  of  atoms  but  combined  into  different  molecules. 
By  further  combinations  of  the  same  elements,  plants  form 
fats  or  oils.  Plants  can  synthesize  sugars  and  fats  because 
water  of  soil  and  carbon  dioxide  of  air  are  available  and 
because  plants  can  use  the  sun's  energy  through  their  photo- 
synthetic  power.  If  the  plant  had  not  thus  made  carbon  fit 
to  eat,  this  earth  would  be  a  No-man's  land.  Ninety-five 



per  cent  of  the  materials  of  our  body  are  made  available 
by  plants'  photosynthetic  power. 

Another  2  per  cent  of  us  is  nitrogen — small  but  important. 
There  is  no  flesh  and  no  protoplasm  without  nitrogen.  The 
air  we  breathe  contains  nitrogen,  but  we  can  no  more  use  it 
than  we  can  the  carbon  dioxide  of  air.  We  get  our  nitrogen 
also  from  plants,  or  from  animals  which  originally  got  it 
from  plants.  Foods  which  contain  nitrogen  are  proteins 
{protos,  first)  or  nitrogenous  foods. 

Proteins,  while  enormously  complex,  are  only  compounds 
of  the  same  three  elements  found  in  sugars  and  fats  plus  nitro- 
gen and  mineral  salts.  Here  is  where  bacteria  come  in. 
Plants  can  fix  their  own  carbon,  but  they  must  go  to  bacteria 
for  their  nitrogen.  As  a  dead  horse  contains  more  nitrogen 
than  an  acre  of  wheat,  his  nitrogen  must  be  kept  in  circula- 
tion. Bacteria  do  the  work.  They  are  the  "middlemen  of 
the  nutritive  chain." 

In  one  gram  of  soil,  says  Jordan,  the  following  bacteria 
have  been  found:  peptone-decomposing,  3,750,000;  urea-de- 
composing, 50,000;  denitrifying,  50,000;  nitrifying,  7,500; 
nitrogen-fixing,  25.  Just  how  bacteria  wreck  a  dead  horse 
is  not  known,  because  so  little  is  known  as  to  the  structure 
of  the  protein  molecule.  But  "eventually,  out  of  the  seething 
caldron  of  molecular  disintegration,  emerge  such  relatively 
simple  bodies  as  organic  acids  and  amins,  mercaptan,  sul- 
phuretted hydrogen,  carbon  dioxide,  and  ammonia." 

The  ammonia  may  be  oxidized  to  nitrites,  and  the  nitrites 
oxidized  to  nitrates.  This  is  nitrification,  and  enormously 
important  for  the  food  supply  of  the  world;  otherwise,  the 
ammonia  from  decaying  plant  life  and  from  manures  would 
not  be  available  for  living  plants.  Sulphur  bacteria  change 
the  sulphuretted  hydrogen  of  mineral  springs  and  decaying 
tissue  to  sulphur,  which  oxidizes  to  sulphuric  acid.  This, 
uniting  with  certain  other  substances,  forms  sulphates;  in  this 
form  plants  can  build  them  into  tissue.  The  nitrogen-fixing 
bacteria  get  their  nitrogen  direct  from  the  air  mixed  in  with 



the  soil.  They  make  their  home  in  little  nodules  of  the  roots 
of  such  plants  as  clover  and  beans,  and  by  enriching  the  soil 
with  nitrogenous  compounds  make  higher  plant  life  possible. 

Bacteria  are  also  the  great  scavengers  of  the  sea,  turning 
loose  carbon  dioxide,  ammonia,  and  ammoniate  materials 
which  algae  build  into  food  compounds  which  make  higher 
sea  life  possible. 

Thomson  relates  how  boxes  of  mud  and  manure  were  set 
alongside  a  fish  pond  which  was  about  to  give  out.  Bacteria 
multiplied,  making  food  for  tiny  protozoa.  These  overflowed 
into  the  pond  and  were  eaten  by  tiny  Crustacea  and  similar 
small  fry.  There  was  now  food  for  fish.  They  multiplied, 
and  were  eaten  by  man.    Fish  is  said  to  be  food  for  brains. 

It  is  not.  But  what  looked  like  mud  became  part  of  man. 
And  at  last  man  used  his  brain,  invented  a  microscope,  dis- 
covered bacteria,  and  opened  a  new  account  with  life. 

To  return  to  our  mutton.  Plants  find  nitrates  in  the  soil, 
also  sulphates  and  phosphates.  These  they  combine  with 
the  elements  they  photosynthesize  into  carbohydrates  and  fats 
to  make  proteins.  Any  bean  can.  But  before  we  can  build 
the  protein  of  a  bean  or  a  peanut,  or  of  milk  or  an  egg  or  a 
chop,  into  our  own  protoplasm,  we  must  reduce  these  complex 
substances  to  simpler  ones.  This  building  of  protein  into 
our  body  is  synthesis,  but  our  synthetic  power  is  far  below 
that  of  plants.  We  must  first  wreck  a  body  that  was  alive  to 
get  the  material  with  which  to  build  our  own  living  body. 

For  example.  We  eat  a  mutton  chop;  we  do  not  build  a 
mutton  chop  into  our  body.  As  mutton,  it  is  of  no  value  to 
us;  we  can  only  use  the  materials  mutton  is  made  of.  By  the 
time  that  chop  is  carted  around  by  the  blood  and  delivered 
at  cell  doorsteps,  it  is  no  more  mutton  than  a  string-bean  is 
a  fish.  We  make  our  own  flesh  out  of  the  same  materials 
fish,  beans,  and  sheep  use  in  making  their  body.  We  recom- 
bine  these  materials  according  to  our  own  formulae.  But  we 
can  only  recombine  them  when  we  have  torn  them  down,  re- 



duced  them  to  materials  the  cells  of  our  body  know  how  to 

That  is  why  we  must  digest  food,  that  is  what  our  digestive 
system  is  for:  to  wreck  the  dead  that  it  may  be  absorbed  into 
the  living.  Anything  that  can  be  absorbed  is  food.  The 
wrecking  process  is  digestion,  work;  energy  is  consumed. 
Food  is  also  stored  energy.  But  before  that  energy  is  avail- 
able for  us,  we  must  reduce  it  to  physiological  fuel  in  our 
alimentary  canal. 


A  white  blood-corpuscle  swallows  a  bacterium  whole.  It 
breaks  it  up  into  bits :  digestion.  Of  these  bits  it  selects  such 
as  it  requires:  absorption.  It  opens  its  body  and  moves  away 
from  such  bits  as  it  does  not  require:  excretion.  Simple 
enough.  Really,  enormously  complicated.  Perhaps  the  most 
complicated  process  known  to  man;  and  no  man  knows  much 
about  it,  even  in  phagocyte  or  ameba. 

Each  cell  in  our  body  is  also  a  living  animal  and  must 
have  its  bits:  building  materials  and  energy  for  building  and 
for  regulation.  To  prepare  bits  fit  for  cell  requirements 
is  the  special  job  of  a  special  group  of  cells  arranged  in 
special  tissues  and  equipped  for  this  particular  purpose:  the 
alimentary  canal  and  accessories,  the  digestive  system.  Its 
sole  business  is  to  reduce  dead  matter  to  such  standard  sub- 
stances as  can  be  delivered  by  the  blood  and  can  be  used  by 
living  cells  for  vital  processes.  Any  matter  which  can  be  thus 
reduced  and  utilized  by  living  organisms  for  vital  processes 
is  food. 

The  alimentary  canal  is  a  single  thirty-foot-long  tube  open 
at  both  ends;  most  of  it  is  coiled  up  in  the  abdomen.  It  is 
lined  with  mucous  membrane  and  coated  with  muscle  which 
contracts  and  relaxes,  forcing  food  forward.  These  muscles 
work  ceaselessly  under  the  drive  of  their  own  engines,  of 
which  there  are  about  2,000,000  per  inch  of  canal.  Valves 



prevent  food  moving  in  the  opposite  direction.  Below  the 
diaphragm  the  canal's  outer  muscle  coat  is  serous,  moistened 
from  the  serum  of  lymph,  as  is  also  the  mesentery  or  ruffled 
peritoneal  fold  which  connects  the  intestine  with  the  back  of 
the  abdominal  wall.  This  makes  them  smooth  and  slippery; 
they  keep  up  their  ceaseless  movements  and  are  not  worn  out 
by  friction. 

Food  is  sampled  in  the  mouth.  If  O.K.'d,  it  is  chewed  fine 
and  mixed  with  saliva,  a  secretion  of  the  salivary  glands. 
This  breaks  it  up,  aerates  it,  moistens  it,  and  makes  it  go 
down  easily:  first  step  in  reduction.  That  step  signals  the 
stomach,  "Get  ready,  food  coming  down";  the  stomach  be- 
gins to  secrete  gastric  juice. 

From  the  mouth,  food  enters  the  cone-shaped  pharynx 
suspended  from  the  skull — the  busiest  spot  in  the  body  at 
meal  times,  especially  if  there  is  conversation.  Its  upper 
mucous  lining  contains  much  lymphoid  tissue.  In  that 
children  develop  adenoids — best  "outgrown"  with  a  knife. 
Adenoid  growths  may  cause  children  to  become  "mouth 
breathers,"  thereby  opening  the  mouth  to  do  the  nose's  work, 
which  is  to  prepare  the  air  for  the  lungs. 

Put  your  hand  on  your  Adam's  apple  and  swallow.  Easy 
as  pie,  but  one  of  the  most  complicated  processes  in  nature. 
The  esophagus  must  be  opened,  and  passages  to  mouth,  nose, 
and  windpipe  must  be  closed.  If  the  windpipe-man  is  asleep, 
food  starts  for  the  lungs  instead  of  the  stomach.  In  the  lungs 
it  is  still  out-of-doors,  subject  to  any  vulture  that  happens 
along.  We  cough  it  up  only  when  tlie  windpipe  cilia  raise  it 
up  within  coughing  distance.  Fortunately,  our  swallowing 
apparatus  works  so  well  that  we  do  not  often  have  to  cough  it 
up.  In  fact,  it  is  so  complicated  and  does  its  work  so  well 
that  a  swallowing  center  in  the  brain  is  assumed. 

Once  food  reaches  the  esophagus  or  gullet,  it  is  gone.  The 
mere  act  of  swallowing  suffices  to  shoot  it  to  the  upper  or 
sphincter  end  of  the  stomach.  Time,  one-tenth  of  a  second. 
If  the  food  is  semi-solid,  it  is  forced  down  by  peristaltic 



waves  in  the  circular  muscles  of  the  esophagus.  Time,  six 
seconds.  Whether  food  is  held  up  by  the  sphincter  before 
passing  into  the  stomach  proper  (and  if  so,  how  long)  is  dis- 

As  ours  is  a  mixed  diet,  we  do  not  require  such  huge  com- 
pound stomachs  as  the  hay-feeders  have.  Ours  is  a  simple 
stomach  with  a  five-pint  or  six-hour  capacity.  That  enables 
us  to  give  much  time  to  other  organs.  Without  a  stomach, 
we  should  have  to  nibble  all  the  time. 

Although  simple,  our  stomach  is  not  so  well  understood  as 
it  might  be.  It  has  three  muscle  layers,  lengthwise,  oblique, 
and  circular.  They  vary  in  thickness  in  different  regions, 
and  contract  and  expand  according  to  the  work  they  have  to 
perform.  Thus,  carbohydrates  receive  stomach  treatment 
different  from  that  given  to  proteins  and  fats.  But  contrac- 
tions begin  a  few  minutes  after  food  enters  the  stomach, 
thereby  further  reducing  it  and  mixing  it  with  gastric  juice, 
which  consists  of  mucin  and  pepsin.  Pepsin  is  a  combination 
of  hydrochloric  acid  and  pepsinogen.  All  three  juices  are 
secreted  by  glands. 

As  a  result  of  mixture  and  contractions,  the  more  liquid 
food,  called  chyme,  is  forced  toward  the  lower  or  pyloric 
(gatekeeper)  end  of  the  stomach.  The  pylorus  opens — so  it 
is  believed — when  the  chyme  pressing  against  it  has  reached 
a  certain  degree  of  acidity.  It  now  enters  the  twenty-foot-long 
small  intestine — the  main  seat  of  digestion  and  absorption, 
the  cleverest  analytical  chemical  laboratory  known  to  science. 
Into  this  intestine  a  few  inches  from  the  stomach  also  come 
bile  from  the  liver  and  a  fluid  from  the  pancreas,  also  the 
intestinal  juice  secreted  by  millions  of  tiny  glands.  Also, 
now  and  then,  the  bacillus  of  typhoid  fever  or  the  ameba  of 

The  lining  or  mucous  coat  of  the  small  intestine  is  easily 
one  of  the  marvels  of  the  world — in  structure  and  accomplish- 
ment. It  is  thrown  into  innumerable  irregular  but  permanent 
folds.    These  increase  the  surface  of  the  mucous  coat  and 



slow  up  the  passage  of  food.  The  surface  itself  is  like  velvet 
or  a  bath-towel,  due  to  four  million  minute  finger-like  pro- 
jections, or  villi.  Each  villus  is  connected  with  a  lymph 
vessel,  an  arteriole,  and  a  vein;  is  inclosed  in  a  layer  of  epi- 
thelium; and  contains  a  muscle.  Under  a  microscope,  each 
villus  can  be  seen  to  lash  about  and  "pump"  up  and  down. 

Beyond  is  the  large  intestine  (cecum,  colon,  rectum),  from 
five  to  six  feet  in  length  and  from  two  and  one-half  to  a  half- 
inch  in  diameter.  Digestive  and  absorption  processes  are  con- 
cluded here.  The  cecum  (blind)  begins  as  a  pouch,  the 
small  intestine  opening  into  it  on  the  side.  At  the  "blind" 
end  is  the  opening  of  the  vermiform  appendix,  also  blind, 
also  a  threat,  and  of  no  known  use  to  man  except  as  a  happy 
hunting  ground  for  gangrene  and  other  bacteria. 

Both  small  and  large  intestines  have  two  muscle  coats: 
the  outer,  longitudinal;  the  inner,  circular.  They  produce 
two  kinds  of  movements:  peristaltic,  or  waves  of  constriction 
which  force  food  onward;  rhythmic — local  constrictions 
which  mass  food  in  spots  or  areas  and  then  break  up  the 
masses.  Such  segregations.  Cannon  finds,  occur  every  two 
seconds.  An  animate  churn,  as  it  were;  and  "keep  moving" 
is  its  motto. 

The  two  great  organs  of  digestion  are  pancreas  and  liver, 
both  marvelous  chemists.  The  pancreas  secretes  enzymes  or 
ferments;  the  liver  works  over  materials  brought  by  venous 
blood  from  intestines,  stomach,  spleen,  and  pancreas.  It 
manufactures  bile;  turns  glucose  into  glycogen;  reconverts 
glycogen  into  glucose  when  ordered ;  and  converts  by-products 
into  urea.  It  is  an  enormously  busy  organ;  the  fires  under 
its  retort  are  always  burning;  its  blood  requirements  alone 
account  for  one-fourth  the  entire  volume  of  blood  in  the  body, 
or  more  than  may  be  found  in  heart,  lungs,  and  great  blood 
vessels  at  any  given  moment. 

No  heat,  no  digestion;  digestion  stops  with  ice  water,  re- 
sumes when  the  blood  has  warmed  the  water  to  blood-heat. 
If  the  blood  gets  chilled,  it  can  find  a  warm  spot  in  the  liver. 




First  on  life's  bill  of  fare  is  water.  No  water,  no  life. 
A  man  of  150  pounds  thoroughly  dried  out  weighs  50  pounds; 
he  has  evaporated  that  much  water.  Bones  are  nearly  half 
water;  our  blood,  90  per  cent;  the  three-months'  human 
fetus,  94  per  cent.  And  half  the  entire  water  content  of 
the  body  is  found  in  muscles.  Without  water,  no  living  proc- 
ess takes  place;  nothing  can  take  its  place  for  washing  away 
our  body's  sins.  Except  for  the  early  hunger  pangs  we  can 
starve  to  death  in  peace,  burning  our  body  for  its  energy, 
dehydrating  our  tissue  for  its  water.  But  without  water  and 
on  the  desert  we  perish  miserably  within  a  few  days,  the 
agony  growing  with  the  hours. 

Other  important  inorganic  foods  are  mineral  salts:  cal- 
cium, iron,  magnesium,  chlorine,  phosphorus,  sulphur,  so- 
dium, potassium.  They  play  important  roles  in  vital  proc- 
esses and  are  found  in  all  protoplasm.  Silicon  and  flu- 
orine are  found  in  certain  tissues  and  are  presumably 
necessary  for  our  existence. 

Iron  in  the  protein  of  the  red  blood-cell  carries  oxygen. 
Fluorine  is  a  minor  tooth-and-bone  builder  and  possibly 
helps  form  the  cement  which  holds  the  cells  together.  Iodine 
is  found  in  the  thyroid  gland.  Silicon  is  found  in  bones,  hair, 
and  the  crystalline  lens  of  our  eye.  Chlorine  is  necessary 
for  the  hydrochloric  acid  of  gastric  juice.  Calcium  and  phos- 
phorus are  necessary  for  bone.  There  is  no  end  to  the  im- 
portance of  these  inorganic  compounds  or  the  uses  the  body 
makes  of  them.  Some  are  especially  essential  during  growth. 
They  are  found  in  the  organic  compounds  of  plant  or  animal 
bodies  which  we  eat  as  food;  they  are  set  free  in  digestion  and 
are  available  for  growth  and  repair. 

The  three  food  groups  proper  are  organic  compounds: 
carbohydrates,  fats,  proteins.  We  eat  more  carbohydrates 
than  fats  or  proteins,  but  they  do  not  remain  with  us  long: 



we  keep  using  them  up  day  by  day.  They  are  the  body's 
primary  sources  of  fuel. 

Carbohydrates  consist  of  sugars  and  starches  and  related 
substances.  Their  chemistry  is  fairly  simple,  their  structure 
complex.  To  get  an  inkling  of  this  structure  is  to  begin  to 
understand  several  important  biologic  and  physiologic  phe- 
nomena and  will  help  explain  why  we  cannot,  for  example, 
digest  sawdust,  and  why  our  liver  must  convert  sugar  to 
starch  or  we  die — without  insulin. 

Note,  again,  that  carbon  atoms  alone  can  form  such  diverse 
substances  as  lampblack  and  diamonds;  the  real  difference 
is  in  the  way  the  carbon  atoms  are  combined  into  molecules. 
Carbon  atoms  are  constituent  elements  of  all  carbohydrates; 
the  hydrogen  and  oxygen  atoms  present  are  always  in  the 
proportions  found  in  water.  But  with  these  water  elements 
the  carbon  enters  to  form  structures  not  only  of  great  com- 
plexity, but  (and  this  is  the  main  point)  of  such  structure 
that  the  molecules  cannot  pass  through  the  wall  of  the  intes- 
tine into  the  blood  or  can  pass  through  the  filter  membrane  of 
the  kidneys.  In  the  one  case  the  molecule  never  gets  into  cir- 
culation, in  the  other  it  passes  out  of  circulation  before  the 
body  cells  can  use  it. 

In  other  words,  food  is  not  what  we  eat,  but  what  can  be 
so  altered  in  the  alimentary  canal  that  it  can  pass  through 
the  canal  wall  into  the  blood-stream  and  can  be  used  by  the 
body  mechanism  for  building,  fuel,  or  storage  purposes.  Most 
foods  are  insoluble  colloids  or  colloidal  in  nature:  during  di- 
gestion they  are  converted  into  soluble  crystalloids;  as  such 
they  can  pass  into  the  blood-stream;  as  colloids  they  cannot. 
By  rough  analogy,  diamonds  are  crystalloid,  lampblack  is 
colloidal.  If  our  digestive  laboratory  could  wreck  the  crystal- 
loid structure  of  a  diamond  molecule  so  that  the  carbon 
atoms  could  pass  into  our  blood-stream,  we  could  be  said  to 
digest  diamonds.  It  cannot  use  the  carbon  atoms  in  a  dia- 
mond because  it  cannot  wreck  the  diamond  molecule.  The 



same  clay-pit  may  furnish  the  mud  for  a  hovel  and  the  brick 
for  a  Michigan  Avenue  French  chateau. 

We  tap  a  maple  tree  and  collect  the  sap;  boil  it  down  to 
sugar,  which  crystallizes  and  is  soluble.  We  eat  the  sugar; 
reduced  further  in  the  alimentary  canal,  it  passes  into  the 
blood-stream  and  is  converted  in  the  liver  to  glycogen  (animal 
starch),  colloidal,  insoluble;  it  can  now  be  stored,  in  muscle, 
for  example.  The  sap  flows  up  the  tree,  the  tree  converts  it 
into  cellulose  and  other  complex  starches;  for  the  tree,  the 
sugar  is  immediate  or  reserve  food  and  cellulose. 

There  is  almost  no  end  to  the  specific  carbohydrates  in  the 
plant  world.  Of  these,  some  twenty  important  kinds  are 
recognized  and  are  divided  into  three  groups. 

The  monosaccharides,  glucoses,  or  simple  sugars,  generally 
contain  six  atoms  of  carbon  (the  hexoses) ;  a  few,  only  five 
(the  pentoses).  Glucose,  dextrose,  or  "grape-sugar,"  is 
found  in  all  animal  tissues  and  in  all  fruit  juices.  Commer- 
cial glucose  is  manufactured  from  starch.  Fructose,  or 
"fruit-sugar,"  is  found  in  honey  and  many  plant  juices. 
Galactose  is  found  in  such  combinations  as  the  cerebrosides 
of  the  brain  and  in  vegetable  gums.  Arabinose  is  found  in 
gum-arabic  and  cherry-tree  gum. 

The  disaccharides,  or  complex  sugars,  are  formed  by  the 
combination  of  two  monosaccharide  molecules,  with  the  elimi- 
nation of  a  water  molecule.  The  three  important  complex 
sugars  are:  sucrose  or  cane-sugar,  in  sweet  juices  of  plants, 
especially  in  sugar-cane,  sorghum  cane,  sugar  maple,  and 
sugar  beet;  lactose  or  milk-sugar,  in  milk;  and  maltose  or 
malt-sugar,  in  malted  grains. 

The  polysaccharides  are  still  more  complex.  They  are 
formed  of  monosaccharides  by  combining  variable  numbers 
of  sugar  molecules  and  eliminating  a  corresponding  number 
of  water  molecules.  The  formula  of  some  polysaccharides 
is  so  complex  as  thus  far  to  baffle  analysis.  Starch,  found  in 
grains,  tubers,  roots,  etc.,  as  stored  energy  for  growth,  occurs 
in  two  forms,  but  whether  the  difference  is  chemical  or  merely 



physical,  and  whether  there  are  one  or  many  kinds  of  starch, 
is  not  known.  But  every  kind  of  plant  has  its  own  distinctive 
starch  grain — otherwise  we  should  not  know  whether  our 
"tapioca"  is  sago  or  mere  potato.  The  starch  grain  of  a  bean 
is  as  unlike  the  starch  grain  of  corn  as  a  grain  of  corn  is 
unlike  a  bean.  Three-fourths  of  the  potato  and  more  than 
half  of  cereals  is  starch.  Sago,  tapioca,  and  arrowroot  are 
almost  pure  starch. 

Other  "starches"  are  glycogen,  found  in  all  animal  tissues 
and  in  yeast;  agar-agar,  found  in  seaweeds;  lichenin,  found 
in  Iceland  moss;  gum-arabic,  found  in  certain  trees;  and 

Cellulose  forms  the  cell-wall  of  plants,  the  hard  part,  the 
fiber;  cotton,  linen,  straw,  wood.  Celery,  beets,  and  turnips 
contain  more  cellulose  than  fruits,  potatoes,  or  flour.  What 
bone  is  to  animals,  cellulose  is  to  plants.  That  is  why  we 
cannot  digest  it  and  why  trees  are  possible.  If  we  could  digest 
it,  sugar  would  be  as  cheap  as  sawdust.  Herbivorous  animals 
can  utilize  it  because  they  have  a  large  cecum  where  cellulose 
can  be  retained  for  a  long  enough  time  to  be  fermented  by 
bacteria.  Our  cecum  is  relatively  smaller  and  does  not  retain 
food  so  long;  the  cellulose  we  ingest  is  excreted. 

Yet  chemically,  cellulose  is  potential  sugar.  Why,  then,  the 
peculiar  qualities  of  wood,  and  why  can  we  not  digest  saw- 
dust? Because,  as  Sponsler  has  recently  shown,  of  its  peculiar 
architecture.  We  cannot  wreck  it.  The  atoms  in  a  cellulose 
molecule  are  arranged  on  an  up-and-down  plan  like  beads  on 
a  string,  and  the  beads  cling  together  for  dear  life.  In  an 
inch-long  piece  of  match  there  are  many  strings  of  "beads"; 
each  string  or  column  contains  about  50,000,000  molecules 
end  to  end.  They  are  pulled  apart  only  with  great  difficulty. 
Wood  is  more  easily  split  lengthwise  than  broken  across, 
more  easily  crushed  lengthwise  than  pulled  asunder,  swells 
sidewise  but  not  lengthwise,  and  is  digested  by  no  animal 
higher  than  protozoa.  Even  termites  or  "white  ants"  can- 
not eat  up  furniture  and  houses  without  the  assistance  of  the 



microorganisms  which  infest  their  alimentary  canal ;  deprived 
of  their  parasitic  digesters,  they  starve  to  death  within  a 

The  second  great  group  of  organic  foods  is  fats;  "compara- 
tively inert  substances  with  long,  complicated  formulae,"  Du 
Bois  characterizes  them.  They  consist  of  one  molecule  of 
glycerin  (an  alcohol)  and  three  of  a  fatty  acid:  palmitic, 
stearic,  oleic,  etc.  Oleic  acid  is  found  in  vegetable  oils:  olive, 
peanut,  corn,  etc.  In  process  of  digestion  such  foods — under 
the  body's  own  steam,  water,  enzymes,  and  mineral  acids — 
are  reduced  to  glycerin  and  fatty  acids.  Outside  the  body, 
they  are  reduced  to  glycerin  and  soap.  The  late  World  War 
fat  shortage  was  due  to  the  wholesale  wreckage  of  fats  to 
recover  the  glycerin  to  make  into  nitroglycerin. 

Lipoids  are  complex  fats,  so  complex  that  their  chemistry 
is  not  well  understood.  One  group  contain  phosphorus  and 
are  thought  to  occur  in  every  living  cell,  especially  in  nerve 
tissues.  Lipoids  are  found  also  in  the  liver,  muscles,  and  yolk 
of  eggs. 

Bulk  for  bulk,  no  food  contains  so  much  potential  energy 
as  solid  fats  and  oils.  When  eaten,  fat  can  be  burned  or 
stored.  The  Eskimo  eat  it  to  keep  warm.  Whales  wrap  a 
foot-thick  layer  around  their  bodies  for  the  same  purpose — 
fat  is  a  great  insulator.  Certain  Ungulates  have  special  fat 
reservoirs  for  lean  days:  the  humps  of  camels  and  drome- 
daries and  of  the  humped  or  sacred  cattle  of  India,  and  the 
tails  of  fat-tailed  sheep. 

Proteins  are  complex  beyond  end.  For  example,  a  mole- 
cule of  cane-sugar  has  a  molecular  weight  of  342;  of  hemo- 
globin, 16,669.  But  that  gives  little  suggestion  of  their 
dissimilar  organization.  It  is  like  comparing  a  grain  of 
sugar  with  an  egg. 

Protein,  freed  of  all  else,  is  colorless,  tasteless,  odorless; 
and  the  basis  of  every  cell  in  life  from  bacterium  and  alga 
to  giant  redwood  and  man.  Apart  from  water,  protein  is  the 
big  constituent  of  eggs,  cereals,  peas,  beans,  lentils,  peanuts, 



fish,  flesh,  and  meat.  The  building-blocks  of  proteins  are 
amino  acids,  organic  compounds  in  which  one  hydrogen  atom 
is  replaced  by  a  chemical  compound  closely  related  to 

Twenty  different  amino  acids  are  known.  Most  of  these 
have  been  discovered  in  the  protein  of  milk,  wheat,  corn, 
gelatin,  chicken,  and  beef.  But  foods  vary  in  the  number 
of  their  amino  acids  and  the  relative  amounts  of  each.  The 
possibilities  in  their  combinations  are  staggering,  chemically 
practically  infinite.  There  is  milk  and  milk,  and  flesh  and 
flesh,  and  eggs  and  eggs :  each  of  its  own  kind.  Just  as  mutton 
fat  built  into  the  human  body  becomes  quite  a  different  kind 
of  fat,  so  with  protein.  From  the  legumin  of  beans  or  the  al- 
bumen of  the  white  of  an  egg,  or  the  gluten  of  wheat,  or  the 
gelatin  of  an  ox's  tendon,  man  builds  his  own  protein  struc- 

But  we  could  not  do  it  without  vitamins.  Until  recently  no 
one  had  ever  seen  a  vitamin,  nor  had  the  chemical  labora- 
tory isolated  one ;  sixteen  years  ago  no  one  had  ever  heard  of 
one.  And  yet  a  real  science  of  food  is  impossible  without  a 
knowledge  of  vitamins.  Without  vitamins  (or  something  just 
as  good)  there  is  no  normal  growth,  health,  reproduction,  or 
living  out  the  span  of  life. 

Scurvy  was  known  to  the  ancient  Greeks,  and  through  the 
centuries  ravaged  armies,  crews  of  ships,  and  explorers  cut 
off  from  fresh  fruit  and  vegetables;  seven  years  ago  no  one 
suspected  the  existence  of  the  antiscorbutic  vitamin.  Thou- 
sands of  children  have  hobbled  out  a  pitiable  existence  on  a 
rickety  frame;  until  recently  no  one  suspected  it  was  because 
of  lack  of  a  specific  mysterious  antirachitic  vitamin  now 
known  to  exist  in  certain  foods.  About  thirty  years  ago  it 
was  known  that  chickens  fed  on  polished  rice  developed  beri- 
beri, and  that  the  same  chickens  fed  on  whole  rice  recovered; 
but  no  one  then  suspected  the  existence  of  an  antineuritic 
vitamin  in  the  polishings  of  rice  or  in  milk. 

Innumerable  experiments  have  now  proved  the  existence  of 



four,  and  possibly  five,  vitamins,  and  their  necessity  for 
human  life  and  the  metabolism  of  all  food.  Because  of  their 
minute  amounts,  their  close  association  with  the  complex  food 
substances,  their  proneness  to  disappear  under  manipulation, 
and  because  no  good  controls  could  be  devised  in  testing,  they 
defied  isolation.  But,  by  relying  on  feeding  and  by  huge 
industry  and  patience,  definite  results  have  been  obtained — 
and  civilization  again  catches  up  with  desiccated  and  tin- 
canned  progress.  In  other  words,  the  human  body  could 
find  all  it  needed  in  the  old  vegetable  garden  and  shambles; 
when  food  began  to  be  refined,  the  vitamins  were  thrown  out 
with  the  screenings. 

Fat-soluble  A  (because  soluble  in  fat),  or  antirachitic 
vitamin,  is  probably  first  in  importance.  All  animals  experi- 
mentally treated  die  if  their  diet  contains  no  vitamin  A.  It 
is  presumably  necessary  for  all  higher  animal  life.  It  is 
known  to  be  necessary  for  growth.  Rachitic  children  pre- 
sumably suff'er  from  lack,  among  other  things,  of  vitamin  A. 
With  vitamin  A  their  bones  assume  normal  growth.  Rachitic 
children  were  numerous  in  parts  of  Europe  during  the  World 
War;  when  the  milk  supply  became  normal,  the  rickets 

Vitamin  A  abounds  in  milk,  cream,  butter,  egg  yolk,  cod- 
liver  oil,  and  presumably  all  animal  fat  except  pork.  It  is 
less  abundant  in  spinach,  tomatoes,  cabbage,  and  lettuce.  It 
is  not  destroyed  by  ordinary  cooking,  but  is  destroyed  by  great 

According  to  a  recent  announcement,  a  semi-crystalline 
product  containing  carbon,  hydrogen,  and  oxygen  has  lately 
been  isolated  by  Takahashi  and  Kawakami  from  cod-liver 
oil,  butter,  and  egg  yolk.  Presumably  it  is  vitamin  A  in 
nearly  pure  form.  Mice  nearly  dead  from  lack  of  fat-soluble 
A  have  been  completely  restored  to  health  by  small  doses 
of  the  substance. 

Water-soluble  B,  or  antineuritic  vitamin,  is  found  in  eggs 
and  seeds.    It  is  essential  to  growth,  and  lack  of  it  is  known 



to  produce  beri-beri.  Seidell  has  recently  isolated  in  nearly 
pure  form  from  brewers'  yeast  a  substance  which  has  anti- 
neuritic  properties.   Presumably  it  is  vitamin  B. 

Water-soluble  C,  or  antiscorbutic  vitamin,  has  thus  far  de- 
fied isolation  in  any  form.  It  is  easily  destroyed  by  alkalies 
and  by  oxidation.  It  is  found  especially  in  lemons,  oranges, 
and  tomatoes;  also  in  all  fruits,  leaves,  and  root  vegetables. 
Without  such  foods,  scurvy.  In  the  World  War  Mesopotam- 
ian  campaign,  Indian  troops  suffered  from  scurvy,  British 
troops  from  beri-beri.  The  Indians  were  living  on  dried  beans 
and  peas,  the  British  on  tinned  beef  and  biscuit.  The  dried 
beans  and  peas  had  lost  their  antiscorbutic  vitamin,  the  white 
flour  its  antiberi-beri  vitamin. 

Vitamin  D,  known  to  accelerate  growth,  is  probably  iden- 
tical with  bios,  a  substance  that  promotes  the  growth  of  the 
yeast  plant.  Its  molecule  consists  of  five  atoms  of  carbon, 
eleven  of  hydrogen,  one  of  nitrogen,  and  three  of  oxygen. 
Enough  bios  to  cover  a  pin-point  will  restore  normal  growth 
in  a  young  animal  stunted  by  a  diet  which  does  not  have 
proper  vitamins. 

Vitamin  X  is  the  latest.  Evans  has  been  experimenting 
with  rats.  If  they  get  no  vitamin  X,  they  become  sterile.  He 
has  also  proved  that  natural  foods  contain  a  substance  or 
substances  essential  for  the  normal  functioning  of  the  mam- 
mary gland.  But  certain  substances  (for  example,  vegetable 
oils)  which  promote  fecundity  do  not  necessarily  improve 

In  short,  there  are  foods  and  foods:  water,  mineral  salts, 
carbohydrates,  fats,  proteins,  vitamins.  Is  sunlight  a  "food" 
also?  It  depends.  Children  and  hogs  that  play  in  the  sun 
need  no  antirachitic  vitamin;  they  do  not  develop  rickets. 
Light  is  a  marvelous  oxidizing  agent.  Foods  with  no  known 
vitamin  A  can  by  ultra-violet  radiation  become  possessed  of 
antirachitic  property.  These  same  rays  get  into  our  skin  and 
"sunburn"  us;  they  will  paralyze  an  ameba  in  a  quarter  of  a 



second,  or  kill  and  tear  its  body  asunder  like  a  bolt  of  light- 
ning in  three  seconds. 

How  much  of  this  or  how  much  of  that  is  good  or  necessary 
or  lethal  for  us  is  a  kind  of  knowledge  that  did  not  seriously 
trouble  our  remote  ancestors,  but  which,  with  our  increasing 
tendency  to  get  away  from  cows,  chickens,  and  gardens,  and 
from  natural  conditions  in  general,  becomes  of  first-rate  im- 
portance. There  was  a  time  when  a  cook  was  a  cook,  good 
or  bad  as  the  case  might  be;  to-day  a  cook  should  be  a  first- 
class  chemist,  the  kitchen  a  chemical  laboratory. 

Meanwhile,  before  we  journey  through  the  canal  with  food, 
it  will  be  well  to  recall  a  fact  of  great  importance.  We  eat 
food — and  should  enjoy  it;  it  is  the  individual,  microscopi- 
cally small  cells  of  our  body  that  are  the  ultimate  consumers 
of  that  food.  If  these  cells  cannot  use  it  (oxidize  it  for  its 
working  energy,  or  build  it  into  themselves  in  repair  and 
growth),  we  may  have  enjoyed  our  meal,  but  our  body  is  as 
unnourished  as  though  we  had  fasted  and  is  poorer  by 
the  amount  of  energy  expended  in  passing  it  through  the 
mill.  It  is  one  thing  for  us  to  eat  food  and  for  our  digestive 
system  to  analyze  it;  it  is  quite  another  matter  (possibly  the 
least  understood  phenomenon  of  living  beings)  for  the  cells 
of  our  body  to  synthesize  it.  Their  astounding  capacity  to 
find  what  they  want  in  astonishingly  dilute  solutions! 

With  one  part  of  carbon  dioxide  in  6,000,000  of  water,  an 
alga  can  grow.  An  ameba  can  find  enough  nitrogen  in  a 
solution  which  contains  one  part  nitrate  per  million  of  water. 
Formaldehyde,  if  it  exceeds  one  part  in  a  thousand,  is  poison 
for  an  alga,  yet  when  the  solution  of  formaldehyde  is  less 
than  lethal  it  will  synthesize  sugar,  if  deprived  of  carbon 
dioxide,  from  the  vapor  of  formaldehyde.  These  figures, 
from  McCollum,  help  us  to  realize  that  our  digestive  system 
must  not  only  so  reduce  complex  molecules  that  they  lose  their 
original  structure,  but  that  the  resultant  substances  must  be 
furnished  to  the  cells  of  the  body  in  proper  solutions  and 
"at  a  favorable  rate." 




The  mechanics  of  digestion  is  simple.  Food  is  chewed 
and  swallowed.  Esophagus  drives  it  to  the  stomach.  Stomach 
kneads  it.  Intestines  roll  it  over  and  around  and  about, 
thoroughly  mixing  it  with  the  juices  of  digestion. 

The  chemistry  of  digestion  is  the  removal  of  one  or  more 
molecules  of  water  (hydrolysis)  through  the  operation  of 
enzymes.  Thus,  foods  are  so  reduced  that  the  substances  of 
which  they  are  composed  can  be  absorbed  by  the  tissues  of 
the  body  or  used  for  fuel  to  make  heat  or  energy. 

In  these  processes,  carbohydrates  are  reduced  to  "simple 
sugars";  fats,  to  glycerin  and  fatty  acids;  proteins,  to  amino 
acids.  These  are  purely  chemical  processes.  The  alimentary 
canal  is  the  chemical  laboratory  where  these  processes  take 
place;  especially  the  small  intestine.  In  chemical  labora- 
tories outside  the  body,  such  processes  take  place  only  with 
high  temperature  and  catalyzers  (dissolvers) . 

Catalysts  are  curious  in  this:  they  hurry  the  reaction,  are 
themselves  unaltered  by  it,  and  to  that  extent  do  not  actually 
take  part  in  it.  Thus,  phosphorus  will  burn  in  oxygen  in  the 
presence  of  water,  the  water  is  unchanged ;  without  the  water, 
the  phosphorus  will  not  burn.  The  water  was  a  catalyzer. 
Again,  cane-sugar  (sucrose)  hydrolyzed  with  hydrochloric 
acid  is  reduced  to  glucose  and  fructose;  at  the  end  of  the 
reaction  there  is  as  much  hydrochloric  acid  as  there  was 
before,  unchanged,  as  good  as  new,  ready  to  do  the  same  thing 
again  when  called  upon.  But  as  it  passes  on  into  the  intestine 
with  food  it  must  be  absorbed — presumably  as  something 
else — and  again  put  into  the  stomach  through  the  secretion 
of  glands.  Sucrose  can  also  be  reduced  to  glucose  and 
fructose  in  boiling  water,  but  it  is  a  slow  process.  The  cata- 
lyzer (hydrochloric  acid)  speeded  the  reaction,  as  will  any 
acid  that  has  electrically  charged  hydrogen  ions.  All  carbo- 
hydrates, fats,  and  proteins  can  be  hydrolyzed  with  great  heat, 
or  with  catalysts. 



During  hydrolysis,  whether  by  boiling  or  with  a  catalyst, 
the  compound  loses  one  or  more  of  its  molecules  of  water. 
The  polysaccharides  hydrolyze  into  several  and  the  disaccha- 
rides  into  two  monosaccharide  molecules. 

Our  body  temperature  is  so  regulated  as  to  remain  con- 
stant at  about  99  degrees.  We  cannot  boil  foods  in  our  body 
laboratory.  The  body  prepares  its  own  catalysts:  enzymes, 
chemical  reagents  that  preside  over  every  chemical  reaction 
in  living  organisms. 

Enzyme  means  "in-leaven";  because,  like  yeast,  it  causes 
fermentation.  But  yeasts  are  unicellular  plants  and  make 
their  own  enzyme,  zymase;  with  that  as  catalyst,  they  ferment 
sugar  to  alcohol,  carbon  dioxide,  etc. 

No  one  has  yet  seen  or  isolated  an  enzyme;  perhaps  no  one 
ever  will.  It  is  said  that  ultra-violet  light  rays  of  suitable 
length  will  bring  about  all  the  reactions  which  can  be  pro- 
duced by  catalyzers;  but  that  gives  us  no  light  at  all  on  how 
enzymes  perform  in  living  bodies. 

An  acid  or  an  alkali  reagent  splitting  a  complex  molecule 
has  been  compared  to  a  hammer  which  smashes  a  clock  and 
then  picks  out  the  undamaged  particles.  But  enzymes,  says 
Bechold,  are  more  delicate  tools:  they  are  like  keys  which 
may  unlock  a  thousand  locks  and  fail  when  worn  out. 

Armstrong  thinks  it  possible  that  enzymes  do  not  exist  as 
entities:  that  they  are  part  of  a  larger  colloid  complex;  and 
that  enzyme  action  is  an  interaction  in  which  water  is  either 
distributed  upon  a  single  molecule  which  is  thereby  resolved 
into  two  others,  or  divided  between  two  molecules,  so  that 
one  is  hydroxylated  and  the  other  is  hydrogenated.  In  the 
strict  sense  of  the  term,  then,  an  enzyme  is  not  an  entity,  al- 
though it  may  have  a  double  function:  it  attracts  the  hydrolyte, 
it  determines  its  hydrolysis — it  is  both  acceptor  and  agent, 
Armstrong  suggests  that  synthesis  in  living  cells  is  also 
brought  about  by  enzyme  action.  Possibly  all  metabolic 
activity  within  or  between  the  cells  of  the  body  may  be  due  to 
enzyme  action.    In  other  words,  the  enzyme  can  not  only 



smash  the  clock  but  can  make  one,  provided  it  has  the 

Enzymes  are  relatively  unstable  and  limited  in  their  action, 
specifically  selective  and  mainly  hydrolytic.  They  activate 
water  molecules.  Hence  it  is  assumed  that  they  are  struc- 
turally related  to  the  substances  (substrates)  on  which  they 
act.  It  is  their  selective  activity  which  forms  the  mechanism 
of  metabolic  regulations;  otherwise  katabolic  or  destructive 
changes  would  be  uncontrolled.  "Once  the  enzyme  complex 
is  formed,  an  electrochemical  current  in  which  active  water 
molecules  take  part  is  completed;  the  energy  being  supplied 
.  .  .  disruptive  changes  take  place,  leaving  the  enzyme  free 
to  form  a  fresh  complex." 

Reference  has  been  made  to  the  storage  of  sugars  and  fats 
in  roots  and  seeds  of  plants.  Something  happens  to  these 
stored  foods  when  the  roots  or  seeds  begin  to  sprout  or  germi- 
nate. The  change  that  then  takes  place  is  due  to  enzyme  ac- 
tion. A  potato,  for  example,  in  a  dry,  cool  cellar,  breathes 
— absorbs  oxygen,  gives  off  carbon  dioxide.  Its  enzymes 
are  quiet.  But  suppose  that  the  potato  is  frozen ;  its  enzymes 
become  active.  Its  amylase  digests  its  starch  to  sugar,  it 
becomes  sweel;  its  protease  reduces  its  proteins  to  amino- 
acids,  it  becomes  bitter.  But  freezing  has  killed  its  germ: 
it  is  a  dead  potato;  it  can  no  longer  defend  itself  against 
bacteria  and,  as  McCollum  says,  soon  rots. 

It  is  presumed  that  the  enzymes  in  the  potato  were  in  an 
inactive  state.  Freezing  activated  them.  During  freezing,  a 
crystalloid  was  added  to  the  colloid  complex  enzyme — it 
became  "activated."  Such  an  activator  of  an  enzyme  is  a 

Pepsin,  for  example,  is  active  in  the  alimentary  canal  only 
when  activated  by  hydrochloric  acid.  The  zymogen  of  pepsin 
is  pepsinogen.  Again,  oxidases  make  biologic  oxidations 
possible  pre  sumably  by  forming  a  system  of  organic  sub- 
stances which  can  lake  up  molecular  oxygen  to  form  peroxide 



and  part  with  one  or  both  atoms  to  another  substance,  the 
transfer  being  hastened  by  a  zymogen,  peroxidase. 

The  enzymes  in  the  potato  in  the  cellar  were  inactive, 
inhibited.  They  are  destroyed  at  the  temperature  of  boiling 
v,^ater — the  boiled  potato  is  still  starch  and  protein.  All 
enzymes  act  best  at  certain  temperatures.  The  enzymes  of 
our  body  find  such  optimum  temperature  because  of  the 
capacity  of  the  blood  to  maintain  a  temperature  at  which  they 
Yvork  best.  Enzymes  are  also  governed  by  their  hydrogen  ion 
concentration.  Enzymes  that  have  an  optimum  reaction  in  an 
acid  solution  will  become  less  active,  or  active  not  at  all,  in 
an  alkaline  solution.  The  mouth  juices  are  alkaline,  the 
gastric  juices  acid;  we  shall  not  expect  to  find  the  same 
enzymes  in  the  mouf.h  that  we  do  in  the  stomach. 

Howell  divides  enzymes  into  the  following  seven  groups: 
proteolytic  or  protein-splitting;  amylolytic  or  starch-splitting; 
lipolytic  or  fat-splitting;  sugar-splitting;  coagulating  (rennin, 
for  example,  which  coagulates  a  soluble  to  an  insoluble  pro- 
tein);  oxidizing,  or  oxidases;  and  deaminizing — whereby 
amonia,  for  example,  is  split  from  alanin,  which  is  thereby 
reduced  to  lactic  acid. 

The  first  four  groups  are  the  important  digestive  enzymes. 
But  they  are  not  confined  to  the  alimentary  canal.  Presum- 
ably both  fat-and  sugar-splitting  enzymes  are  present  in  the 
blood  and  other  tissues,  especially  muscle. 

The  fact  that  many  enzymes  exist  in  an  inactive  or  zymogen 
stage  both  in  secreting  cells  and  after  secretion  and  require 
activating  before  they  function,  suggests  another  interesting 
and  important  biologic  phenomenon:  the  capacity  of  the  blood 
and  other  tissues  to  form  dissolvers  or  antibodies  to  foreign 
protein  substances.  We  shall  have  a  look  at  these  antibodies 
presently;  we  now  resume  our  voyage  through  the  alimentary 

During  digestion,  food  is  mechanically  reduced  to  particles 
that  can  be  carried  in  the  watery  fluid  of  the  canal.  In  the 
canal,  it  is  mauled  about  and  churned  up  with  the  agents  and 



reagents  of  chemical  action.  It  is  always  meeting  new  phy- 
sical and  chemical  conditions.  In  the  mouth  food  is  mixed 
with  saliva,  of  which  we  secrete  from  one  to  two  quarts  a 
day.  It  contains  two  enzymes  (ptyalin  changes  starch  to 
dextrin  and  maltose,  maltase  changes  maltose  to  glucose)  and 
mucin,  a  lubricator. 

Saliva  is  slightly  alkaline;  the  gastric  juice  of  the  stomach 
is  strongly  acid  and  contains  three  enzymes:  pepsin,  splits 
proteins;  rennin,  coagulates  milk  and  converts  casein  to 
paracasein;  lipase,  splits  fats  in  emulsion,  such  as  cream. 
The  stomach,  then,  is  the  important  digester  of  proteins, 
especially  meat,  flesh,  fowl,  fish,  eggs,  and  milk.  How  the 
stomach  can  secrete  a  free  acid  such  as  hydrochloric  from 
blood  which  is  a  neutral  fluid,  is  as  yet  an  unsolved  mystery. 
It  does.  That  acid  is  a  fine  antiseptic  or  disinfectant  and 
checks  bacterial  growth,  except  that  which  causes  acid  fer- 
mentation. But  too  much  acid  makes  for  hyperacidity :  gas- 
tritis, gastric  ulcers.  The  flow  of  gastric  juice  is  inhibited 
by  emotional  stress  and  pain,  by  anything  which  rouses  the 
sympathetic  nervous  system  to  activity. 

When  food  reaches  the  intestine  it  has  lost  its  looks  and 
much  of  its  nature — digestion  begins  in  the  mouth.  In  the 
intestine  it  loses  everything  it  was  as  food  for  eye  or  mouth, 
to  become  something  that  a  cell  can  use  or  spend.  It  meets 
with  about  a  pint  and  a  half  of  pancreatic  juice:  very  alka- 
line, rather  sticky,  and  charged  with  three  enzymes:  trypsin, 
leaves  the  pancreas  as  trypsinogen  (a  zymogen)  and  becomes 
trypsin  in  the  small  intestine;  it  is  a  proteoclast,  breaks  down 
proteins  into  their  constituent  animo-acids;  amylase,  acts  like 
ptyalin,  hydrolyzing  starch  to  maltose;  and  lipase  or  steap- 
sin,  which  hydrolyzes  or  saponifies  fats  into  glycerin  and 
their  constituent  fatty  acids.  Lipase  is  also  found  in  the 
mammary  glands,  muscles,  liver,  blood,  etc.  It  seems  that  it 
also  acts  as  enzyme  in  the  synthetic  processes  involved  in 
reconverting  the  glycerin  and  fatty  acids  of  lard,  butter, 



cream,  oil,  etc.,  into  the  kind  of  fat  we  store  in  our  adipose 

Food  in  the  small  intestine  also  meets  a  secretion  of  the 
glands  of  the  intestine,  the  succus  entericus.  That  intestinal 
juice  contains  six  enzymes:  enterokinase,  a  zymogen  which 
converts  trypsinogen  to  trypsin;  erepsin,  completes  any 
unfinished  business  of  trypsin  and  pepsin;  nuclease,  acts  on 
the  nucleic  acids  of  the  nucleoproteins ;  maltase,  converts  the 
maltose  and  dextrin  of  starches  to  dextrose;  invertase,  con- 
verts cane-sugar  to  dextrose  and  levulose;  lactase,  converts 
milk-sugar  to  dextrose  and  galactose. 

Secretin  is  also  an  assumed  constituent  of  intestinal  juice. 
Its  chemical  nature  is  not  known.  It  is  probably  not  an 
enzyme.  It  seems  to  act  as  a  messenger.  Carried  to  the 
pancreas,  it  stimulates  that  gland  to  send  its  juice  to  the 

Food  in  the  small  intestine  also  meets  the  bile,  a  constant 
secretion  of  the  liver,  stored  in  the  gall-bladder,  and  deliv- 
ered periodically  to  the  intestine  when  needed.  Bile  is  a 
thick,  bitter,  alkaline  liquid.  Its  color,  varying  from  golden 
yellow  to  dark  olive  green,  is  due  to  iron  pigments  from 
broken-down  red  blood-cells.  Some  of  these  pigments  are 
returned  to  the  liver  via  the  portal  vein;  some  are  eliminated 
by  the  alimentary  canal  and  color  the  excreta.  Bile  pigment 
which  gets  into  the  skin  colors  it  yellow  and  is  called  jaun- 
dice, but  is  not  infectional  jaundice. 

Bile  also  carries  two  acids  or  "salts,"  secretions  of  the 
liver  cells.  Their  function  is  not  definitely  known.  They 
are  partly  returned  from  the  intestine  to  the  liver  and  pre- 
sumably stimulate  the  liver  to  further  activity.  They  prob- 
ably assist  in  turning  fat  into  soap  in  the  small  intestine  and 
so  make  its  absorption  possible.  They  apparently  help  dis- 
solve cholesterol. 

Cholesterol,  a  "solid  alcohol,"  is  ingested  with  food,  but, 
as  shown  by  Gall,  can  be  synthesized  by  the  liver.    It  occurs 



in  every  cell  of  our  body,  especially  in  nerve  cells;  it  is 
found  in  the  secretions  of  the  fat  or  oil  glands  of  the  skin 
(in  sheep's  wool  also,  and,  when  extracted,  called  lanolin) ; 
it  is  found  in  blood,  milk,  yolk  of  egg,  kidneys,  and  adrenal 
glands.  It  stimulates  growth  of  cancer.  When  it  crystallizes 
in  the  human  gall-bladder,  it  is  called  cholelith  (gallstone) ; 
when  in  the  sperm  whale,  ambergris.  Wliy  gallstones,  and 
all  that  cholesterol  is  or  does,  are  not  well  known;  this  is 
partly  due  to  its  stubborn  resistance  to  biological  and  chem- 
ical reactions. 

"Synthesized  by  the  liver" — I  should  have  said  "liver 
cell."  Of  which  there  are  many  many  millions,  for  the  liver 
is  the  largest  gland  in  the  body.  Each  liver  cell  is  an 
"organ."  In  each  cell  (according  to  Bechold)  are  225,000 
million  water  molecules,  2,900  million  crystalloid  molecules, 
166  million  fat  molecules,  and  53  million  protein  molecules; 
and  each  molecule  bafflingly  complex  beyond  power  of 
description!  That  cell  is  more  than  a  mere  cell;  it  is  a  busy 
little  world.  No  wonder  that  a  liver  which  has  to  handle 
copper  from  worm-stills  or  copper  vessels  for  twenty  years 
gets  discouraged  and  catches  atrophic  cirrhosis.  The  human 
liver  is  organized  to  deal  with  iron,  sugar,  etc.,  but  not  with 
copper.  Presumably  this  copper  hastens  the  break-up  of  red- 
blood  cells.  Too  much  pigment  in  the  liver.  The  cells 
sicken  and  die. 

All  in  all,  a  normal  adult  pours  about  five  quarts  of 
digestive  juices  into  his  intestine  each  day.  About  four  and 
one-half  quarts  of  these  juices  are  reabsorbed  and  presum- 
ably worked  over  again  for  secretion  by  the  various  glands 
of  digestion. 

Why  does  not  the  intestine  digest  itself?  Or  tapeworms — • 
they  are  in  the  presence  of  trypsin,  a  powerful  enzyme?  But 
juice  of  a  dead  tapeworm  mixed  with  juice  of  the  pancreas 
stops  trypsin  action.  It  seems  as  though  the  tapeworm  has  a 
substance  which  inhibits  the  action  of  trypsin;  with  that  it 



saves  itself  from  being  digested.  Otherwise  it  could  not  stop 
the  action  of  the  enzyme. 

The  alimentary  canal  does  not  digest  itself  because  it  is 
protected  by  the  slimy  coat  of  mucus  secreted  by  its  living 
lining  cells.  But  when  there  is  nothing  in  the  canal  for  the 
secretions  to  work  on  and  the  pancreas  is  artificially  stimu- 
lated to  discharge  its  secretion  into  the  canal,  an  irritation 
is  set  up  as  though  brought  about  by  digestion. 

Food  begins  to  enter  the  large  intestine  about  two  hours 
after  it  passes  the  mouth,  but  not  until  about  ten  hours  later 
has  the  last  of  the  meal  left  the  small  intestine.  The  secretion 
of  the  large  intestine  is  alkaline,  contains  mucin,  but  no 
enzymes.  The  digestive  enzymes  from  the  small  intestine 
continue  if  there  is  any  unfinished  business.  The  time 
required  for  food  to  make  the  entire  canal  journey  is  from 
twenty-four  to  thirty-six  hours. 

The  chief  digestive  change  in  the  large  intestine  is  prob- 
ably due  to  bacteria,  the  "intestinal  flora."  These  multiply 
so  rapidly  that  about  half  the  contents  of  the  lower  part  of 
the  large  intestine  are  bacteria,  excreted  at  the  rate  of  about 
130,000,000,000,000  a  day.  They  are  of  no  knoiun  positive 
benefit.  They  may  act  on  otherwise  indigestible  cellulose; 
they  may  synthesize  proteins  from  ammonium  salts  in  such 
form  that  the  protein  can  be  absorbed;  in  which  case  they 
should  not  be  outlawed,  because  bacteria  are  cheaper  than 

The  small  intestine  also  has  its  bacterial  colonies  which 
are  responsible  for  ammonia  and  at  least  five  kinds  of  intes- 
tinal gases.  Their  action  is  chemically  not  unlike  that  of 
enzymes;  but  whether  bacteria  are  positively  harmful  in  our 
alimentary  canal  is  as  yet  a  moot  and  unsettled  problem.  As 
the  stomach  is  sterilized  by  the  gastric  juice,  bacteria  do  not 
grow  there  and  it  is  comparatively  free  of  bacteria.  But 
they  may  escape  the  action  of  hydrochloric  acid  inside  solids 
or  undigested  particles,  and  so  pass  on  into  the  small  intes- 
tine, where  they  can  grow.    Bacteria  are  sometimes  found  in 



hens'  eggs;  they  got  in  during  the  hours  the  egg  was  in 
transit  from  the  ovary  and  before  the  shell  was  formed. 


Digested  food  in  the  alimentary  canal  is  as  useful  to  the 
body  as  when  in  the  butcher  shop  or  grocery  store.  It  must 
pass  from  the  canal  into  the  blood  before  the  body  can  eat 
it.    This  is  called  absorption. 

What  is  absorbed?  What  is  a  "square  meal"  when 
digested?  Sugars  and  starches  have  become  "simple" 
sugars;  fats  have  become  glycerin  and  fatty  acids.  Huge 
protein  molecules  of  from  12,000  to  15,000  weight  and  con- 
sisting of  a  hundred  or  more  amino-acid  molecules  linked 
together,  have  been  dehydrolyzed  into  their  eighteen  to 
twenty  constituent  amino-acids  and  certain  mineral  salts.  One 
of  these  salts  may  be  silicon — invaluable  for  glass  eyes  and 
all  glass;  absorbed  within  the  blood  and  carried  to  the  eye, 
it  is  built  into  the  crystalline  lens.  Only  the  diamond  is 
harder  than  silicon.  We  cannot  eat  silicon;  our  digester 
finds  it  in  milk  and  bamboo  shoots. 

Alcohol,  pepper,  mustard,  etc.,  are  absorbed  in  the 
stomach;  especially  alcohol,  and  so  readily  that  little  of  it 
reaches  the  small  intestine.  Water  is  not  absorbed  in  the 
stomach,  nor  to  any  great  extent  in  the  small  intestine ;  chiefly 
from  the  large  intestine. 

The  small  intestine,  with  its  sixteen  square  feet  of  absorb- 
ing surface,  is  the  great  absorber,  as  it  is  the  great  digester, 
of  food.  During  absorption,  the  sugars  and  amino-acids 
pass  from  intestine  to  the  capillaries  in  its  walls  and  are 
then  passed  into  general  circulation?  Not  at  all;  they  are 
carried  by  the  portal  vein  to  the  great  pool  in  the  blood 
stream,  the  liver.  We  shall  see  why  presently.  During 
absorption,  soaps,  fatty  acids,  and  glycerol  are  resorbed  and 
are  carried  away  as  chyle  to  the  lacteals  of  the  lymphatic 
system  and  so  into  general  circulation  via  the  lungs.    It  is 



this  neutral  or  "emulsified"  fat  that  gives  chyle  its  milky 
look,  hence  the  lymphatics  of  the  intestine  are  called 

But  how?  The  intestine  is  not  a  tube  of  blotting  paper 
or  of  charcoal;  its  surface  is  a  solid  wall  of  living  cells. 
How  do  these  lifeless  building-blocks  get  through  that  wall? 

Over  a  salt  solution  in  a  bowl  place  a  layer  of  pure  water. 
Salt  molecules  enter  the  top  layer.  This  is  diffusion.  Water 
and  oil  do  not  mix;  such  a  liquid  is  indiffusible. 

On  one  side  of  a  membrane  in  a  bowl  place  a  salt  solution; 
on  the  other  side,  pure  water.  Water  molecules  will  enter 
the  salt  solution.  This  is  osmosis:  the  less  dense  solution 
(water)  will  pass  toward  the  stronger  solution.  Osmotic 
pressure  lifts  water  from  the  soil  to  the  top  of  the  highest 

On  one  side  of  the  membrane  place  a  solution  of  white 
of  egg  and  salt;  on  the  other  side,  water.  Salt  will  leave 
the  egg  and  enter  the  water  until  the  concentration  of  salt 
on  each  side  is  equal.    This  is  dialysis. 

These  three  laws  of  physics  help  us  to  understand  what 
goes  on  during  absorption.    But  there  are  difficulties. 

Why  did  the  salt  only  leave  the  egg,  why  did  not  the  egg 
also  pass  through  the  membrane?  Egg  is  colloidal.  Its 
molecules  are  too  large  to  diffuse  through  membranes. 
Inorganic  salts  are  diffusible:  they  are  crystalloids;  their 
molecules  are  relatively  small.  Digestion  is  largely  a  process 
of  breaking  large  molecules  into  their  constituent  relatively 
small  molecules. 

It  is  one  thing  to  know  that  a  certain  organic  compound 
building-block  called  an  amino-acid  is  set  free  in  the  process 
of  digestion;  it  is  quite  another  question  how  this  block  gets 
through  that  wall  of  live  cells.  And  still  another  question — 
and  one  of  life's  deep  secrets — ^how  this  or  that  cell  builds 
that  block  into  its  own  structure  and  at  the  same  time  stamps 
it  with  its  seal  of  individuality  so  that  it  is  now  unique  both 
for  the  species  and  for  the  kind  of  tissue  it  is  in.   What  was 



a  non-specific  simple  compound  has  now  been  synthesized 
by  the  cell  into  its  own  complicated  specific  self.  When 
we  learn  how  the  cell  does  that,  we  may  hope  to  build  a 
living  cell. 

Consider  that  the  sugars,  amino-acids,  and  fatty  acids  have 
passed  that  wall  of  living  ceils,  v/hat  then?    Much  is  known. 

The  sugar  or  glucose  is  stored  by  the  liver  as  glycogen. 
Why  stored,  why  glycogen?  Sugar  is  crystalline,  soluble; 
if  left  in  the  blood,  it  would  be  washed  out  in  the  urine; 
glycogen  is  colloidal,  insoluble.  As  a  result  of  this  storage, 
the  blood  sugar  concentration  may  remain  normal  at  one 
part  in  a  thousand.  When  the  body  needs  fuel,  the  liver 
reconverts  glycogen  to  sugar  and  sends  it  out  into  the  blood. 
Small  amounts  of  glycogen  are  also  stored  in  the  muscles 
and  all  active  tissues.  Excess  sugars  are  synthesized  into 

The  fats  are  carried  about  by  the  blood  and  taken  up  by 
the  tissues  that  need  fuel;  oxidized,  they  supply  energy. 
Wlien  thus  burned,  the  "ashes"  are  carbon  dioxide  and  water. 
All  fat  not  required  is  stored:  adipose  tissue.  Fat.  People 
get  fat  because  they  eat  more  sugars  and  fats  than  they  use — 
and  unless  they  contemplate  fasting  or  fear  starvation,  they 
carry  a  senseless  and  an  unnatural  burden. 

For  biologic  oxidations,  fats  are  relatively  the  most  impor- 
tant foods.  One  pound  of  fat  has  a  fuel  value  equal  to  two 
and  one-quarter  pounds  of  carbohydrates  or  proteins. 

No  body  is  built,  or  kept  alive  and  warm,  without  energy. 
The  body  requires  enough  energy:  to  keep  alive  (depending 
on  age  and  other  factors)  and  to  run  the  digestive  system 
(often  called  "cost  of  digestion") ;  to  work;  to  keep  in  repair. 
Say  2,500  calories  for  a  man  of  170  pounds.  Of  these 
calories,  from  10  to  15  per  cent  should  be  in  proteins.  If 
one  does  manual  work,  or  loves  to  store  fat,  the  calories  may 
be  increased  up  to  10,000. 

The  sugars  are  carried  to  the  liver  first;  so  are  the  amino- 
acids,  the  raw  material  from  which  the  body  builds  itself, 



with  which  it  keeps  itself  in  repair.  "Repair"  is  not  to  be 
thought  of  merely  as  new  tissue  to  heal  a  wound  or  new 
protoplasm  to  replace  that  being  constantly  shed  by  nails, 
hair,  and  the  epidermis  of  the  skin.  There  must  be  the  raw 
materials  for  the  building  of  new  blood-cells,  for  glandular 
action,  for  hormones  and  enzymes,  and  for  the  eternal  wear 
and  tear  of  heart,  nerve  tissues,  and  all  the  organs  which 
function  ceaselessly  until  chilled  in  death.  The  blood  is 
their  environment.  From  the  blood  they  must  obtain  such 
amino-acids  as  they  require,  when  they  require,  and  in  proper 
solution.  Too  great  concentration  is  fatal  to  certain  tissues, 
fatal  to  heartbeat;  too  great  concentration  of  the  end-product 
of  their  metabolism,  ammonia,  is  likewise  fatal.  The  kidneys 
play  their  part,  but  they  can  be  damaged  by  too  much  of 
the  digested  products  as  well  as  by  too  much  of  the  end- 
products  of  metabolism.  It  is  because  the  liver  receives 
the  amino-acids  direct  from  the  small  intestine  that  they  pass 
into  general  circulation  slowly  and  in  proper  concentration. 
When  the  liver  functions  badly  from  disease,  the  amino-acids 
are  fed  into  general  circulation  faster  than  the  tissues  can 
use  them  up;  they  escape  in  abnormal  amounts  through  the 
kidneys.  While  amino-acids  have  no  "threshold  value"  for 
the  kidney  filter,  we  lose  little  if  they  enter  the  blood-stream 

In  the  blood-stream,  the  amino-acids  are  carried  about 
for  the  use  of  such  tissues  as  require  them.  What  is  not 
required  is  normally  broken  down  in  the  liver — "deamin- 
ized."  The  non-nitrogenous  element  is  then  useful  for  fuel 
and  may  be  converted  by  the  liver  into  glycogen  and  stored. 
The  nitrogenous  element,  ammonia,  is  turned  into  urea  and 
handed  over  to  the  kidneys  for  elimination. 

When  the  body  eliminates  as  much  nitrogen  as  it  receives 
in  the  form  of  protein  nitrogen,  the  body  is  in  "nitrogen 
equilibrium":  it  is  not  burning  flesh,  but  fuel.  If  the  bal- 
ance is  in  favor  of  intake,  the  body  is  growing:  "taking  on" 



flesh.  Flesh  is  not  fat,  although  it  can  be  burned  as  fat,  as  it 
is  during  starvation. 

Why  so  much  bother?  Why  not  eat  glucose,  glycerin, 
soap,  and  amino-acids,  and  save  wear  and  tear  of  teeth,  action 
of  thirty  feet  of  canal,  and  secretions  of  countless  glands? 
Why  not  predigested  food?  Sounds  reasonable.  But  try  it. 
Try  a  meal  of  amino-acids.  Even  a  rat  will  starve  to  death 
rather  than  eat  a  mixture  of  amino-acids.  They  are  about 
as  unpalatable  as  anything  could  be;  in  milk,  ham  and  eggs, 
string  beans,  lamb  chops,  and  the  innumerable  forms  in 
which  we  ingest  amino-acids,  they  are  palatable. 

Even  pure  sugar  as  the  sole  source  of  carbohydrates  would 
soon  sicken  us — nor  could  we  taste  anything  else.  Starches — 
in  dozens  of  forms — are  in  themselves  tasteless,  but  carry 
odors  and  flavors  which  make  them  appetizing.  And  as  for 
a  diet  of  fatty  acids  and  soaps!  Good  butter  is  good,  but 
its  butyric,  caproic,  caprylic,  and  capric  acids  taste  bad  and 
smell  worse. 

Further,  foods  in  concentrated  crystalloidal  form  would 
irritate  the  mucous  lining  of  the  canal  and  cause  the  blood 
to  give  up  its  salts  to  the  canal.  A  bacterium  cannot  digest 
salt  or  sugar;  salt  or  sugar  can  "digest"  a  bacterium,  absorb 
its  juices;  but  a  bacterium  can  live  in  a  weak  solution  of 
sugar  or  salt. 

In  short,  as  McGollum  (from  whom  I  have  drawn  freely) 
says,  it  is  neither  possible  nor  desirable  to  nourish  the  body 
with  predigested  foods.  But  when  it  becomes  necessary  to 
resort  to  rectal  feeding,  predigested  foods  are  necessary; 
otherwise  they  could  not  be  absorbed,  because  the  large 
intestine  is  little  concerned  in  digestive  processes. 

Life  is  protoplasm.  Protoplasm  is  a  solution — mostly 
water.  Water  comes  before  and  after  food  in  life.  In  all, 
from  eight  to  ten  glasses  a  day  or  the  equivalent  in  water- 
laden  food.  If  alcohol  is  consumed,  less  water  is  required; 
the  end-products  of  an  alcohol  "jag"  are  carbon  dioxide  and 
water.    This  brings  us  back  to  the  blood  again. 




There  are  more  things  in  the  blood  than  were  dreamt  of 
in  Horatio's  philosophy  or  Moses  could  have  imagined  when 
he  said  that  "the  life  of  the  flesh  is  in  the  blood."  Had 
blood  been  better  understood  in  1799,  Washington  would  not 
have  been  bled  to  death  to  cure  him. 

While  it  is  important  that  we  do  not  lose  sight  of  the 
individuality  of  the  body  or  of  the  organism  as  a  whole,  and 
the  fact  that  parts,  organs,  even  cells,  as  parts,  organs,  or 
cells,  are  meaningless,  it  is  equally  important  to  remember 
that  the  body  is  made  up  of  cells.  These  cells  have  sur- 
rendered certain  functions  to  groups  of  cells,  tissues,  and 
organs,  but  they  are  the  ultimate  living  units  of  the  living 
body;  they  must  get  their  face  next  to  food,  air,  and  water, 
and  have  their  garbage  removed.  The  blood  performs  this 
service.  The  blood  is  their  physical  and  chemical  environ- 
ment. It  is  an  integrating  organ  to  the  extent  that  it  keeps 
the  cells  at  a  proper  temperature  and  furnishes  them  with  the 
proper  hydrogen  ion  concentration,  the  right  kind  of  mineral 
salts,  sufficient  oxygen  and  fuel  for  energy  requirements,  and 
the  proper  amounts  of  brick  and  mortar  for  growth  and 
repair.  A  single-celled  organism  has  such  matters  in  its  own 
hands,  but  the  cells  in  our  body  depend  on  the  blood.  The 
blood  is  their  world;  without  the  blood  they  are  as  hope- 
lessly isolated  from  life-yielding  energies  as  would  be  a 
child  on  a  cake  of  ice  in  an  antarctic  sea.  The  blood  itself, 
without  arteries,  veins,  capillaries,  and  lymphatics,  is  as 
valueless  as  spilled  milk;  it  can  function  only  in  its  own 
transportation  system.  That  functioning  depends,  as  does 
cell  and  tissue  metabolism,  on  the  fact  that  the  membranes 
of  cells  and  tissues  have  different  degrees  of  permeability 
to  different  substances. 

In  one  sense  blood  itself  is  a  tissue;  it  has  its  own  metabo- 
lism, it  has  its  millions  of  living  cells.  But  its  main  function 
is  transportation;  it  carries  that  out  through  the  transporta- 



tion  or  circulatory  system.  That  system  maintains  a  day 
and  night  service,  remarkable  as  system  and  in  the  nature 
of  the  material  it  brings  to  the  door  of  the  myriad  cells  of 
our  body.  It  does  more  than  deliver:  it  collects  poisonous 
wastes  and  hands  them  over  to  the  kidneys  to  get  rid  of. 
That  system  breaks  down  with  fatal  results. 

A  160-pound  man  has  about  eight  pounds,  or  four  quarts, 
of  blood.  He  may  lose  up  to  one  and  one-half  quarts  at  one 
time  and  recover.  Within  a  day  or  two  he  has  as  much 
blood  as  before;  it  may  be  a  week  before  his  blood  regains 
its  former  composition. 

Under  the  microscope,  blood  is  a  pale  yellowish  fluid 
in  which  float  two  kinds  of  minute  cells,  the  red  and  white 
corpuscles.  The  fluid  is  the  plasma;  90  per  cent  water,  10 
per  cent  reduced  groceries  and  meats,  chemicals,  drugs.  It 
also  contains  many  substances  the  physiologist  is  unable  to 
make  or  to  isolate.  Whatever  it  is  that  the  endocrines 
secrete,  and  whatever  it  is  that  enzymes  are,  the  blood 
transports  them.  It  also  transports  such  gases  as  oxygen, 
carbon  dioxide,  and  nitrogen;  such  inorganic  salts  as 
chloride,  carbonate,  sulphate,  and  phosphate  of  sodium,  cal- 
cium, magnesium,  potassium,  and  iron;  such  nitrogenous 
extracts  as  urea,  uric  acid,  creatinin,  ammonia  salts,  amino- 
acids,  and  phosphatives;  many  proteins;  sugars,  fats,  lactates, 
and  cholesterol;  five  or  six  antibodies,  and  special  substances 
supposed  to  be  concerned  in  the  clotting  of  the  blood. 

Blood  issuing  from  an  open  blood  vessel  (or  drawn  from 
the  body)  clots,  jells;  this  closes  or  seals  the  wound.  This 
clotting  is  a  unique  process,  though  gums  play  a  similar 
role  in  the  vegetable  kingdom.  The  very  act  of  opening  a 
blood  vessel  seems  to  set  up  a  reaction  in  the  blood  itself. 
The  blood  contains  an  enzyme  called  thrombin  (clot),  which, 
in  shed  blood,  activates  a  soluble  fibrinogen  in  the  blood 
to  become  an  insoluble  fibrin  of  very  fine  needle-like  crystals. 

Fibrin  collects  at  the  wound  and  permits  the  passage  of 
the  watery  serum,  but  holds  back  the  red  corpuscles  and  the 



platelets.  They  become  enmeshed  in  the  fibers,  "clot";  the 
opened  blood  vessel  is  sealed,  the  flow  of  blood  is  stayed. 
But  the  white  corpuscles  squirm  through  the  fibrin,  as  a 
snake  does  through  a  brush  heap. 

Clotting  may  generally  be  hastened  by  hot  towels  or  con- 
tact with  any  foreign  substance,  by  rest,  and  by  the  poison 
from  certain  snakes.  But  the  blood  of  some  individuals 
clots  dangerously  slowly;  they  may  even  bleed  to  death  from 
a  slight  wound.  True  hemophilia  (bleeder's  disease)  is  said 
to  be  hereditary. 

Clotting  can  be  prevented  by  a  secretion  called  hirudin 
from  the  mouth  glands  of  the  pond  leech;  it  is  important 
to  a  leech  that  its  victim's  blood  should  not  clot!  It  is 
important  that  our  blood  should  clot  when  a  blood  vessel  is 
injured.  Presumably  the  adrenal  gland  is  responsible  for 
heightening  the  capacity  of  the  blood  to  clot  under  certain 
psychological  stresses.  But  a  foreign  substance,  even  a 
bubble  of  air,  in  a  blood  vessel  may  cause  a  clot,  thrombosis. 
If  the  blood  can  absorb  the  clot,  no  damage  is  done;  if  not, 
and  if  the  clot  is  carried  to  some  point  where  it  blocks  circu- 
lation, it  is  fatal.  A  clot  on  the  brain  or  in  the  heart  is 
almost  always  fatal. 

The  personal  service  of  collection  and  delivery  is  made 
by  the  lymph,  the  body's  middleman,  the  final  link  in  our 
transportation  system. 

We  rarely  see  lymph.  Rarely  hear  of  it  until  it  goes 
wrong,  then  we  know  it  as  edema,  or  dropsy;  if  it  is  in  the 
legs,  as  elephantiasis — legs  as  big  as  elephants'.  Something 
stops  up  the  lymphatics;  lymph  collects,  the  part  of  the  body 
affected  swells  up  with  lymph. 

Lymph  (water)  is  blood  plasma  that  filters  through  the 
microscopic  walls  of  the  capillaries.  It  bathes  the  cells  and 
effects  exchange  of  materials,  leaving  behind  what  the  cells 
need,  carrying  off  what  is  not  needed.  Then  it  joins  the 
great  drainage  system  whereby  blood  is  returned  to  the  heart. 

Lymph  has  its  own  system,  lymph  vascular  system.  This 



begins  with  minute  lymph  capillaries  into  which  the  lymph 
passes  by  filtration.  These  unite  in  larger  vessels,  die 
lymphatics;  these  empty  into  ducts  which  pour  their  contents 
into  two  large  veins  which  unite  to  form  the  upper  vena  cava. 
Thus  the  blood  has  made  a  round  trip:  it  is  again  in  the 
heart.  Before  it  is  put  into  general  circulation  again,  it 
must  be  aired. 

Why  do  we  not  all  have  elephantiasis?  What  keeps  the 
lymph  moving?  Movement,  for  one  thing.  Every  body 
movement  alters  the  shape  and  size  of  many  muscles.  This 
puts  pressure  on  the  lymph  vessels,  which  grow  larger  toward 
the  main  ducts  emptying  into  the  veins.  The  lymph  cannot 
flow  backward — or  downhill,  as  it  should  because  of 
gravity — because  the  lymphatics  are  beset  with  valves,  as  are 
the  veins,  especially  in  the  arms  and  legs.  The  valves  lie 
flat  against  the  wall  of  the  vessels  as  long  as  the  current 
flows  in  the  right  direction.  Reversing  the  current  forces 
the  valves  out  and  closes  the  tube.  Lymph  can  only  flow 
in  one  direction,  toward  the  heart. 

In  joining  the  larger  lymphatics,  lymph  passes  through  one 
or  more  of  our  700  lymph-nodes.  Some  are  no  bigger  than 
pinheads,  some  as  large  as  olive  seeds.  They  abound  in 
the  armpits,  groins,  thorax,  neck,  and  mesentery.  They  are 
not  true  "glands";  they  secrete  nothing.  But  they  are  our 
good  friends.  They  police  the  blood.  Outposts  held  by 
sentinels  that  never  sleep;  always  on  the  lookout  for  foreign 
substances,  especially  bacteria. 

In  fact,  a  lymph-node  is  barbed-wire  entanglement  for 
bacteria ;  they  never  get  beyond  a  node  without  a  fight.  The 
fight  is  bloodless,  for  neither  combatant  has  any  blood,  but 
it  is  always  a  fight  to  the  death.  Then  it  is  that  we  discover 
our  lymph-nodes:  the  fight  inside  causes  the  node  to  swell 
with  inflammation.  We  met  such  inflamed  nodes  in  child- 
hood and  called  them  "waxing-kernels." 

The  fight  is  between  white  corpuscles  and  bacteria.  If  the 
cells  win,  we  hear  no  more  about  it.    If  bacteria  win,  they 



tell  us.  There  is  nothing  so  immodest  or  shameless  as  an 
average  bacterium,  or  can  do  so  much  good  and  so  much 
damage  in  proportion  to  its  size.  It  can  move  mountains 
and  destroy  cities. 

If  lymph  is  blood  filtered  through  tissue,  how  do  white 
corpuscles  get  into  lymph?  The  same  way:  they  lengthen 
and  filter  through.  We  hear  much  of  these  white  corpuscles 
or  leukocytes  (white  cells).  They  are  not  well  understood, 
nor  is  it  known  how  many  kinds  there  are,  where  they 
originate,  how  long  they  live,  why  they  multiply — now 
rapidly,  now  slowly — and  what  finally  becomes  of  them. 
Some  are  believed  to  originate  in  bone  marrow,  others  in 
lymph-nodes.    They  lead  a  fairly  independent  existence. 

Presumably  they  break  down  dead  tissue  cells,  carry  fat 
from  the  intestines  into  the  lymph  and  so  to  the  blood,  help 
stabilize  the  protein  content  of  the  blood,  and  possibly  lib- 
erate a  substance  which  assists  in  blood  clotting.  They  may 
destroy  the  worn-out  red  cells  in  the  spleen  and  liver.  Some 
eat  bacteria. 

Evidently  bacteria  au  naturel  are  not  palatable  and  some- 
what indigestible.  One  kind  of  leukocyte  is  supposed  to 
remedy  that.  The  blood  plasma  itself  is  credited  with  a 
substance  which  makes  phagocytes,  as  the  "eater-cells"  are 
called,  greedy  for  bacteria.  This  substance  is  called  opsonin, 
Greek  for  "preparing  a  banquet."  With  no  opsonin  in  the 
blood,  a  phagocyte  eats  only  one  bacterium  at  a  time;  with 
opsonin,  he  takes  them  on  in  bunches,  possibly  because  it 
causes  bacteria  to  herd.  The  result  is  the  same:  the 
phagocytes  engulf  them  faster. 

Injury  to  or  inflammation  in  any  part  of  the  body  sets  up 
irritation.  Blood  hustles  phagocytes  up  to  the  injured  part; 
it  gets  red  from  the  red  corpuscles  of  the  blood.  If  bacteria 
are  present,  a  fight  is  on.  If  phagocytes  win,  they  crawl 
back  into  the  blood  again.  If  they  lose,  the  bacteria  kill 
them  and  also  tissue  cells.  Pus  forms.  Pus  is  dead  tissue 
and  white  corpuscles,  plasma  from  injured  blood  vessels,  and 



dead  and  living  bacteria.  A  scar  on  the  neck  may  mark 
the  spot  where  tubercular  bacilli  were  held  up  by  a  lymph 
gland  and  lost  a  fight  with  phagocytes. 

Our  "resisting  power"  is  good  when  we  have  enough 
leukocytes.  We  generally  have  enough  when  our  transporta- 
tion system  is  all  in  order. 


The  business  of  the  transportation  system  is  to  deliver 
fresh  blood — "pasteurized,"  aerated,  and  heated  to  the 
proper  temperature — to  several  billion  cells  twice  a  minute, 
every  minute  of  life.  That  is  big  business  and  of  vital 
importance;  and  no  man-made  transportation  system  comes 
within  miles  of  it  for  honesty,  accuracy,  or  efficiency.  Nor 
has  man  yet  made  as  fine  a  tube  as  an  artery  or  as  good  a 
pump  as  the  heart. 

Cut  a  thin  section  across  a  small  artery  and  put  it  under 
a  microscope.  It  has  three  coats  of  muscle.  The  fibers 
of  the  outer  coat  run  lengthwise  and  are  dense;  they 
strengthen  the  artery,  enable  it  to  resist  undue  expansion, 
make  it  hard  to  cut  or  tear.  The  inner  or  lining  coat  is 
extraordinarily  smooth;  the  blood  hustles  on  with  next  to  no 
friction.  The  middle  coat  is  in  two  layers  of  fine  muscle 
fibers  circularly  interlaced ;  one  layer  is  elastic,  the  other  con- 
tractile. The  thickness  of  this  coat  varies  according  to  the 
traffic  it  bears;  the  larger  the  artery,  the  thicker  its  walls. 

With  every  heartbeat,  every  inch  of  artery  in  the  body 
expands  and  contracts.  In  fifty  years  they  have  expanded 
and  contracted  about  three  billion  times.  When  this  middle 
coat  clogs  up  with  lime  salts  they  harden,  lose  their  elasticity. 
Arteriosclerosis  probably  increases  the  rate  of  flow  in  the 
arteries — but  does  not  make  for  "high  blood  pressure."  Fat 

Arteries  carry  blood  from  the  heart.  The  great  artery, 
or  aorta,  leading  direct  from  the  heart,  is  about  an  inch  in 



diameter.  It  soon  branches;  the  branches  branch;  on  and 
on;  they  become  smaller,  smaller,  and  finally  discharge  their 
tiny  rivulets  into  capillaries  so  minute  that  it  would  take 
thousands  of  them  to  hold  as  much  blood  as  the  aorta.  Even 
the  corpuscles  in  the  blood  must  travel  through  them  Indian 
file,  and  at  that  it  is  often  a  tight  squeeze. 

The  heart  is  simply  the  central  power  house;  the  arteries, 
simply  the  tubes.  But  with  the  capillaries  the  transport 
system  becomes  a  special  service;  without  them,  the  blood 
could  not  do  its  big  work.  They  form  a  vast  network  through- 
out the  entire  body  except  in  hair,  nails,  cuticle,  cornea  of 
the  eye,  and  cartilage;  that  is  why  cartilage  is  so  white. 

The  blood  returns  through  veins,  also  tubes  and  very  tiny 
at  first  where  they  begin  to  gather  up  the  minute  trickles 
after  the  blood  has  done  its  work  in  the  capillaries.  The 
tubes  grow  larger  and  larger  as  vein  after  vein  keeps  dis- 
charging its  contents,  and  become  at  last  the  two  great  vence 
cavcB  which  deliver  the  blood  to  the  heart. 

The  heart  is  easily  understood  if  one  does  not  look  at  it; 
then  it  seems  hopelessly  complicated.  Think  of  it  as  two 
pairs  of  cubes,  one  pair  on  top  of  the  other.  The  two  top 
cubes  are  shaped  like  ears,  hence  their  name,  auricles.  They 
receive  blood:  the  left  auricle,  from  the  lungs  by  means  of 
the  two  pulmonary  veins;  the  right  auricle,  from  the  upper 
and  lower  part  of  the  body  by  the  two  vence  cavce. 

The  two  bottom  cubes  are  round  like  little  bellies,  hence 
their  name,  ventricles.  They  expel  blood:  the  left  ventricle, 
to  the  body  via  the  aorta ;  the  right  ventricle,  to  the  lungs  via 
the  pulmonary  artery. 

Why  does  the  heart  beat  75  times  every  minute?  How 
does  the  blood  know  where  to  go?  The  second  question  is 
easy,  the  first  is  now  being  solved..  But  beat  it  does,  from 
four  months  before  birth  until  life  snuffs  out  with  its  last 
beat.  Forty  million  times  a  year.  The  work  it  does  is 
literally  staggering.  More  amazing  is  the  fact  that  it  will 
go  right  on  beating  after  it  has  been  removed  from  the  body; 



kept  moist  in  a  neutral  salt  solution  (sodium,  calcium,  and 
potassium  salts)  and  fed  a  little  sugar,  it  will  beat  for  days. 
Muscle  tissue  cut  from  the  body  will  also  grow  and  beat 
rhytlimically  under  stimulus,  but  there  is  an  automatic  action 
to  the  heartbeat  which  as  yet  has  not  been  solved. 

The  heart  is  striated  and  "involuntary"  muscle — not 
under  control  of  the  will.  Only  the  heart  has  this  combina- 
tion. The  result  is  a  specific  dynamic  system  which  functions 
in  connection  with  certain  nutrients  and  ions.  Seventy-five 
beats  per  minute  is  a  normal  average;  but  among  the  soldiers 
of  a  single  company,  all  presumably  normal  and  all  under 
similar  conditions,  it  was  found  to  vary  from  42  to  108. 

The  heart  beats  according  to  its  past  as  well  as  to  its 
present  experiences;  emotions,  diseases,  narcotics,  drugs, 
muscular  activity,  rate  of  metabolism,  etc.,  all  enter  into  the 
count.  The  bigger  the  body,  the  slower  the  beat:  25  per 
minute  for  an  elephant;  50  for  a  donkey;  70  for  men;  80 
for  women;  90  for  youth;  140  for  a  newborn;  150  for  a 
rabbit;  175  for  a  mouse.  The  more  active  the  body,  the 
faster  the  heartbeat.  I  can  save  my  heart  20,000  beats  a 
day  by  remaining  quietly  in  bed.  It  has  been  experimentally 
determined  that  when  the  pulse  is  forced  up  to  135  per 
minute,  the  subject  becomes  uncomfortable;  above  160  it  is 
very  distressing  and  fairly  unbearable,  although  one  was 
recorded  of  184  per  minute. 

The  blood-stream  is  kept  to  its  course  by  valves.  For 
example,  blood  returned  from  the  body  by  the  two  vencs 
cavce  fills  the  right  auricle  and  the  right  ventricle:  the  two 
at  the  time  are  one  chamber.  The  auricle  contracts,  forcing 
more  blood  into  the  ventricle  below.  As  the  contraction 
slows  up,  a  valve  between  auricle  and  ventricle  is  forced 
shut  by  the  pressure  of  blood  in  the  ventricle.  This  ventricle 
now  contracts,  forcing  the  blood  through  the  now  open  valves 
into  the  pulmonary  artery  and  so  on  into  the  lungs.  It  is 
returned  by  the  pulmonary  veins,  and  enters  the  left  auricle 
and  ventricle.    Left  auricle  contracts,  distending  the  left 



ventricle;  then  the  valve  between  them  closes.  Then  the  left 
ventricle  contracts,  forcing  the  blood  into  the  aorta.  After 
it  has  traversed  the  body  it  is  returned  by  the  vence  cavce  to 
the  right  auricle. 

Around  it  goes.  It  cannot  go  astray,  for  it  circulates  in 
a  closed  system;  valves  in  the  heart  and  in  the  veins  prevent 
it  from  going  in  the  wrong  direction.  The  heartbeat  forces 
it  to  keep  moving.  The  vasomotor  apparatus,  through  nerve 
connections  with  the  muscle  walls  of  the  arterial  system, 
controls  the  amounts  of  blood  flow  to  the  various  tissues  and 
organs  of  the  body. 

This  transportation  system  must  supply  its  own  needs  also. 
Arteries  and  veins  are  tubes  of  living  tissue;  they  must  have 
their  blood.  They  receive  it  from  their  own  system  of 
arteries,  capillaries,  and  veins:  the  vasa  vasorum,  blood 
vessels  which  supply  nourishment  to  the  coats  of  other  blood 


The  left  half  of  the  heart  contains  arterial  blood;  the 
right,  venous.  The  walls  of  the  two  auricles  are  relatively 
thin;  of  the  ventricles,  thick — that  of  the  left  three  times 
that  of  the  right;  it  has  three  times  as  big  a  job.  The  left 
ventricle  drives  blood  into  the  aorta  with  a  velocity  of  about 
thirty  feet  a  second.  But  before  that  blood  returns  to  the 
left  ventricle,  it  must  make  two  long  journeys.  First  it  visits 
every  nook  and  cranny  in  the  body,  and  is  returned  by  the 
vence  cavce  to  the  right  auricle.  That  completes  the  systemic 
or  general  circulation  and  requires  twenty-three  seconds. 

From  the  right  auricle  the  blood  passes  down  into  the 
right  ventricle,  and  by  it  is  driven  through  the  pulmonary 
arteries  to  the  lungs.  There  it  takes  the  air.  It  then  returns 
by  the  two  pulmonary  veins  to  the  left  auricle,  and  thence 
into  the  left  ventricle.  That  completes  the  pulmonary  circu- 
lation and  requires  about  fifteen  seconds.   The  blood  is  now 



ready  to  be  expelled  by  the  left  ventricle  into  the  aorta,  to 
be  put  again  into  general  circulation. 

"Taking  the  air"  is  a  vital  process — in  fact,  no  process  is 
more  vital;  but  before  looking  at  it,  let  us  see  how  the  new- 
born prepares  for  that  momentous  first  step,  one  of  the  most 
interesting  adaptations  in  life. 

The  four-months-old  fetus  is  attached  by  its  umbilical 
cord  to  the  now  fully  formed  placenta,  consisting  largely  of 
connective  tissue  and  blood  vessels  which  interlace  with 
blood  vessels  in  the  uterus.  But  there  is  no  direct  exchange 
of  fetal  blood  with  that  of  the  host;  only  by  diffusion  through 
permeable  membranes  can  the  fetus  derive  nourishment  and 
oxygen  from  its  host's  blood  vessels.  This  it  does  through 
the  umbilical  vein.  Through  the  two  umbilical  arteries  it 
delivers  to  the  placenta  the  end-products  of  fetal  metabo- 
lism— chiefly  carbon  dioxide,  which  diffuses  from  placental 
blood  vessels  into  the  blood  vessels  of  the  host  and  is  by  her 
eliminated  in  her  lungs. 

After  birth,  the  umbilical  cord  is  tied  and  cut.  This  cuts 
off  the  newborn's  oxygen  intake  and  carbon  dioxide  outlet; 
it  must  make  vital  rearrangements.  Quick. 

A  blood  clot  forms  between  the  navel  and  the  liver  in  what 
was  the  umbilical  vein;  that  stops  circulation  in  that  direction 
and  prevents  the  infant  from  bleeding  to  death.  As  a  result 
of  that  clot,  two  blood  vessels  cease  to  function  and  pass  off 
the  stage  forever.  Another  clot  forms  in  the  vessel  which 
connected  the  aorta  with  the  pulmonary  artery;  and  it  goes 
out  of  circulation.  Two  other  clots  form;  and  two  other 
vessels  begin  to  obliterate  themselves. 

One  other  change  is  necessary  before  the  infant  is  a  full- 
fledged  air-breather.  Up  to  the  time  of  birth  there  is  an 
opening  between  the  right  and  left  auricles,  the  foramen 
ovale.  But  with  the  closing  of  the  vessel  from  the  pulmonary 
artery  to  the  aorta  the  blood  is  forced  into  the  lungs,  thence 
into  the  pulmonary  veins,  thence  into  the  left  auricle. 
Pressure  in  the  left  auricle  closes  the  foramen  ovale  between 



the  two  auricles.  It  stays  closed;  thereafter  there  is  no 
opening  between  left  and  right  auricles.  Sometimes  it  does 
not  close  tight;  venous  blood  mixes  with  arterial.  The 
result  of  this  mixture  is  impure  blood;  cyanosis — "blue 
babies,"  even  blue  adults.  If  the  opening  is  too  great,  the 
mixture  is  fatal;  not  enough  blood  gets  the  air. 

This  separation  of  the  heart  into  right  and  left  halves, 
thereby  keeping  venous  from  arterial  blood,  made  constantly 
warm  blood  possible,  and  is  found  only  in  birds  and  mam- 
mals. Lower  vertebrates  have  impure  blood,  and  change 
their  temperature  with  the  thermometer.  Failure  of  the  new- 
born's foramen  ovale  to  close  is  a  memento  of  reptilian  days; 
death  follows  because  our  metabolic  processes  are  set  for 
pure  warm  blood. 

The  clots  and  the  closure  of  certain  blood  vessels  and 
foramen  ovale  completely  alter  the  newborn's  circulation; 
it  must  now  get  its  oxygen  by  its  own  efforts.  It  draws  its 
first  breath. 

This  is  a  big  job  for  a  small  child.  Lungs  at  birth  are 
solid;  they  must  be  shaken  out,  filled  up,  as  one  would  a 
balloon.  The  balloon  the  infant  has  to  fill  is  several  times 
larger  than  its  body.  Lungs  are  like  enormously  complex 
sponges — minute  pockets  or  air  cells,  all  opening  into  fun- 
nels, these  into  tubes  or  bronchioles,  these  into  right  and  left 
bronchi,  these  finally  into  the  trachea  or  windpipe. 

Trachea  and  bronchi  are  lined  with  the  microscopic 
chimney-sweep  cilia.  They  move  foreign  particles  up  within 
reach  of  the  coughing  mechanism.  When  the  cilia  are 
damaged  by  bad-cold  germs,  we  cough  up  floods  of  mucus, 
dead  cilia  cells. 

If  the  infant  takes  its  first  breath  through  its  nose,  it  sets 
a  good  example  for  itself;  that  is  what  the  nose  is  for. 
Internal-combustion  engines  work  best  if  given  warm  air. 
The  infant  is  such  an  engine.  Its  nose  is  like  a  scroll  radi- 
ator, thereby  exposing  a  large  area  of  membrane  to  contact 
with  its  first  and  every  breath.    That  breath  drawn  through 



the  nose  filters,  warms,  and  moistens  the  air,  important 
qualities  for  every  breath.  The  nose  prepares  the  air  for 
the  lungs  as  the  mouth  prepares  food  for  the  stomach.  It 
"samples"  air  by  the  sense  of  smell,  as  the  mouth  samples 
food  by  the  sense  of  taste.  If  the  air  is  no  good,  we  hold 
our  nose ;  if  the  air  is  cold,  the  vasomotor  system  sends  more 
blood  to  the  nasal  membrane. 

The  infant  is  in  contact  with  the  air  through  the  skin  of  its 
body.  When  its  lungs  are  expanded,  another  surface  is  in 
contact  with  the  air;  this  lung  surface  is  from  ninety  to  one 
hundred  times  greater  than  body  surface.  An  average  man 
has  about  one  square  yard  of  skin  surface,  about  ninety 
square  yards  of  lung  surface. 


After  our  first  breath,  our  lungs  are  never  again  free  from 
air.  They  must  have  thin  walls,  to  let  oxygen  into  the  blood 
and  carbon  dioxide  out;  without  air  they  would  collapse. 
The  passages  leading  to  the  air-sacs  do  not  collapse,  because 
they  are  held  open  by  stout  rings  of  cartilage.  Even  if 
removed  from  the  body  and  punctured,  the  collapse  of  the 
small  tubes  entraps  air  into  the  air-sacs.  Lungs  that  will 
float  cannot  have  belonged  to  a  stillborn;  butchers  call  them 
"lights" — they  are  lighter  than  water. 

There  are  always  about  two  pints  of  residual  air  that  we 
cannot  budge.  But  with  great  effort  we  can  expel  the  sup- 
plemental air — about  three  pints.  With  no  effort  at  all  we 
inhale  and  exhale  tidal  air — about  one  pint.  With  another 
effort  we  can  inhale  about  three  pints  more — complemental 
air.  The  maximum  amount  of  air  that  can  be  forcibly 
expelled  after  a  deep  inspiration  is  about  one  gallon.  This 
is  vital  capacity;  it  differs  with  individuals,  and  diminishes 
if  we  give  our  lungs  no  hard  work  to  do. 

We  breathe  faster  when  a  certain  nerve  center  in  the  brain 
tells  the  inspiration  muscles  to  speed  up.    The  nerve  gets 



its  cue  from  carbon  dioxide.  There  is  always  carbon  dioxide 
in  the  blood,  but  it  plays  second  fiddle  to  oxygen.  When 
there  is  too  little  oxygen  or  too  much  carbon  dioxide,  we 
breathe  faster.  The  air  we  inhale  has  21  per  cent  of  oxygen, 
.04  per  cent  carbon  dioxide.  The  air  we  exhale  has  16 
per  cent  oxygen,  4  per  cent  carbon  dioxide,  which  means 
that  in  the  lungs  the  air  lost  5  per  cent  of  its  oxygen  and 
gained  4  per  cent  carbon  dioxide.  No  matter  how  cold  and 
dry  the  inhaled  air,  the  expired  air  is  blood  hot  and  saturated 
with  moisture. 

A  thin,  moist  membrane  of  the  lungs  separates  air  from 
blood.  On  the  air  side  is  a  high  percentage  of  oxygen.  On 
the  blood  side,  a  high  percentage  of  carbon  dioxide.  An 
exchange  of  gases  takes  place  through  the  membrane.  As  a 
result,  the  blood  brought  to  the  lungs  by  the  pulmonary 
arteries  loses  about  10  per  cent  of  carbon  dioxide;  the  blood 
carried  back  to  the  heart  by  the  pulmonary  veins  gains  about 
10  per  cent  of  oxygen. 

It  requires  less  than  two  seconds  for  the  blood  to  take  the 
air  and  exchange  its  crimson  for  a  scarlet  hue.  Arterial 
blood  is  scarlet.  If  "blue"  blood  is  a  caste  sign,  certain 
shell-fish  are  the  Brahmins  of  creation;  their  blood  oxygen- 
carrier  is  not  the  iron  of  hemoglobin,  but  the  copper  of 
hemocyanin.  This  copper  is  blue  in  the  crab  and  tastes  like 
copper  in  the  European  oyster. 

Aerated  blood  begins  its  long  round  through  the  body  as 
soon  as  it  is  shot  into  the  aorta  by  the  left  ventricle.  The 
blood  delivers  its  oxygen  as  the  iceman  leaves  ice — according 
to  the  needs  of  families  on  its  route,  making  the  round  trip 
every  half  minute.  An  organ,  gland,  muscle  at  rest  does  not 
need  much,  but  activity  anywhere — in  organ,  gland,  muscle, 
what  not — means  an  extra  supply.  The  heart  itself  will  use 
twice  the  oxygen  at  one  time  it  does  at  another.  At  meal 
times  the  intestines  require  extra  large  supplies.  Even  mild 
thinking  causes  the  brain  to  double  its  usual  demand.  "Fast 
thinking"  may  even  require  fast  breathing.    Whatever  con- 



sciousness  is,  it  goes  out  like  a  candle  when  the  oxygen  is 
cut  off. 

Oxygen.  Oxygen.  Everywhere  we  go,  every  time  we  turn 
around,  always,  as  long  as  we  live,  the  tissues  of  our  body 
are  crying  for  oxygen  and  freedom  from  carbon  dioxide, 
else  they  choke  to  death.  And  our  bellows  keep  working 
away:  60  breaths  a  minute  for  the  newborn,  40  for  the  child, 
20  for  the  adolescent,  16  to  18  for  the  adult.  About  one 
breath  for  every  four  heartbeats  is  a  normal  average. 

The  air  we  breathe  is  about  80  per  cent  nitrogen;  as  it  is 
an  inert  gas,  we  absorb  none  of  it.  But  under  high  atmos- 
pheric pressure,  as  in  a  diving  bell  or  caisson,  nitrogen  is 
dissolved  in  the  blood  and  in  the  tissues.  If  the  pressure 
is  suddenly  released,  the  gas  cannot  remain  in  solution  but 
forms  bubbles,  and  the  blood  effervesces  like  a  bottle  of  pop. 
(A  nitrogen  bubble  lodged  in  a  vital  spot  is  as  fatal  as  a 
blood  clot.)  This  makes  for  stiff  muscle  joints — "bends," 
the  workmen  call  them.  If  the  pressure  is  slowly  relaxed, 
bubbles  do  not  form,  and  the  gas  in  the  tissues  is  carried 
by  the  blood  to  the  lungs  and  nitrogen  equilibrium  with  the 
gases  of  the  atmosphere  is  again  restored. 

Equilibrium.  The  body  is  wonderfully  balanced.  Vital 
processes  other  than  growth  are  equilibrizing  processes. 
When  the  equilibrium  is  upset,  the  body  begins  to  readjust. 
It  works  like  a  defensive  army,  massing  its  forces  against 
the  greatest  dangers.  The  blood  is  the  marvelous  distributor, 
regulator,  restorer,  provider,  of  forces.  When  one  thinks 
of  the  billions  of  individual  cells  the  blood  serves,  it  is  truly 
the  Little  Friend  of  All  the  World. 

It  is  significant  that  too  much  carbon  dioxide  rather  than 
too  little  oxygen  sets  the  bellows  working  faster.  If  we  are 
only  short  of  oxygen  we  can  fall  asleep,  even  in  death;  the 
lungs  rise  and  fall  until  the  last.  We  can  burn  ourselves 
up  slowly;  but  from  the  smoke  of  the  fires  of  action  we  must 
be  promptly  delivered. 

Not,  Give  the  lungs  air;  but.  Give  the  air  carbon  dioxide. 



That  purifies  the  blood.  And  if  respiration  cannot  be 
resumed  otherwise  in  an  asphyxiated  person,  give  his  respira- 
tory center  carbon  dioxide — then  it  will  order  the  lungs  to 
action.    But  if  the  respiratory  center  is  dead,  it  is  too  late. 


Abel  withdrew  from  one  dog  in  one  day  twice  the  volume 
of  its  blood.  The  dog  should  have  died  twice,  but  inasmuch 
as  the  professor  collected  and  returned  all  its  red  blood 
corpuscles,  it  lived.  When  he  withdrew  only  60  per  cent 
of  the  dog's  blood  and  did  not  promptly  restore  the  red 
corpuscles  to  its  blood,  it  died. 

Our  lungs  are  valuable,  but  we  really  breathe  through  the 
hemoglobin,  or  respiratory  pigment  of  the  red  corpuscles. 
Blood  plasma  is  complex;  the  red  corpuscles,  or  erythrocytes 
(red-cells),  are  inconceivably  complex.  They  are  born  in 
the  red  marrow  of  bones  and  have  nuclei  as  have  other 
cells.  On  entering  the  blood  stream  they  lose  their  nuclei 
and  assume  their  characteristic  disk  or  muffin  shape;  they 
can  no  longer  grow,  and,  after  ten  or  fifteen  days'  work,  die 
and  are  broken  up  in  the  liver  or  spleen.  In  fishes,  amphibia, 
and  camels,  the  nuclei  are  not  lost  in  the  blood. 

Each  red  corpuscle  is  about  1/3200  of  an  inch  in  diameter, 
1/12400  of  an  inch  thick.  Yet  they  make  up  about  35  per 
cent  of  the  volume  of  the  blood — or  enough  to  fill  a  pint  cup. 
In  a  spoonful  of  blood  there  are  about  30,000,000,000,  or 
in  an  adult  male  about  25,000,000,000,000;  a  few  billions 
less  in  an  adult  female.  Her  blood  and  her  lips  are  no  less 
red,  nor  has  she  less  capacity  to  blush  or  acquire  a  red  nose, 
nor  has  she  less  iron -in  her  constitution;  simply  less  body, 
and  consequently  need  for  less  blood.  Anemic  persons  have 
either  fewer  red  cells  or  less  iron  in  the  cells  they  have. 
The  proportionate  number  present  at  any  one  time  varies 
according  to  many  factors — constitution,  nutrition,  and 
especially  with  age,  being  most  numerous  in  fetal  life.  In 



women,  they  increase  in  number  during  menstruation,  dimin- 
ish during  pregnancy. 

Red  blood-cells  carry  oxygen.  That  makes  them  red  and 
they  make  the  blood  red.  They  are  soft,  flexible,  elastic. 
Had  a  camel  these  qualities  equally  highly  developed,  he 
could  easily  pass  the  needle's  eye.  Carried  by  the  blood  to 
the  lungs,  they  squeeze  through  spaces  as  small  as  the  uni- 
verse is  big,  resuming  their  disk-like  shape.  With  nothing 
between  them  and  the  air  but  a  thin  membrane,  they  detach 
oxygen  and  squeeze  through  into  the  blood  again.  They  are 
small,  but  their  combined  surface  area  is  nearly  4,000  square 
yards,  with  nearly  90  square  yards  of  lungs  for  them  to 
operate  on.  Of  course,  only  a  small  portion  of  them  are 
present  in  the  lungs  at  any  one  instant.  The  blood  lugs  them 
about  from  cell  to  cell.  Any  cell  needing  fresh  air  then  and 
there  gets  it;  and  gets  rid  of  carbon  dioxide,  which  the  blood 
carries  to  the  lungs.  If  it  carries  much  we  take  a  long  breath, 
or  several. 

While  it  has  long  been  known  that  the  hemoglobin  carries 
oxygen,  it  has  only  recently  been  established  that  it  also 
carries  most  of  the  carbon  dioxide.  According  to  Du  Bois, 
sufferers  from  faulty  circulation  show  lack  of  oxygen  and 
excess  of  carbon  dioxide;  their  blood  does  not  move  fast 
enough  through  the  lungs  for  the  red-cells  to  get  rid  of  their 
carbon  dioxide.  When  the  saturation  of  oxygen  in  venous 
blood  falls  below  20  per  cent,  cyanosis  results. 

Ordinarily,  it  is  not  lack  of  oxygen  or  excess  of  carbon 
dioxide  in  crowded  rooms  that  makes  for  distress;  it  is  the 
heat,  humidity,  and  odors  of  unwashed  bodies.  Gases  diffuse 
through  insignificant  cracks  in  walls,  around  windows,  under 
doors.  It  was  the  heat  and  humidity  that  were  so  fright- 
fully fatal  to  the  crowd  in  Calcutta's  Black  Hole,  not  lack 
of  oxygen  or  excess  of  carbon  dioxide. 

While  the  air  we  breathe  ordinarily  contains  about  .04  per 
cent  of  carbon  dioxide,  a  submarine  crew  will  work  for  days 
in  air  containing  2.5  per  cent  and  suffer  no  ill  effect.  With 



5  per  cent  carbon  dioxide  in  the  air,  we  double  our  rate 
of  breathing;  when  it  rises  above  8  per  cent,  we  are  in  real 
distress.  Further  increase  begins  to  slow  up  the  rate  of 
breathing,  with  death  when  it  reaches  40  per  cent. 

Too  much  oxygen  is  equally  fatal.  Ordinarily,  air  con- 
tains about  21  per  cent  of  oxygen — more  than  we  need  or 
can  use.  Nor  does  breathing  pure  oxygen  increase  the 
oxygen-content  of  the  hemoglobin  (oxyhemoglobin).  But 
pure  oxygen  at  a  pressure  of  three  atmospheres  (one  for 
every  thirty-three  feet)  leads  to  convulsions  and  death. 
Workers  in  caissons,  diving  bells,  and  submarines  may  die 
from  oxygen  poisoning  in  ordinary  air  at  five  atmospheric 
pressure;  fifteen  atmospheres  is  always  fatal. 

At  about  26,000  feet  above  sea-level,  the  oxygen  concentra- 
tion falls  to  7  per  cent — a  test  for  an  aviator's  fitness.  Even 
at  15,000  feet  many  suffer  severe  "mountain  sickness" 
(anoxemia),  and  lose  consciousness  above  20,000  feet.  But 
by  compensatory  action  in  heart  and  blood  vessels,  most 
people  can  soon  become  "acclimated"  to  mountain  heights. 

Just  how  the  respiratory  pigment  jettisons  carbon  dioxide 
and  takes  on  a  cargo  of  oxygen  while  in  the  lungs  is  no  more 
known  than  just  how  an  ameba  or  a  cold  potato  breathes,  or 
how  the  cells  of  the  tissues  of  our  body  exchange  carbon 
dioxide  for  oxygen.    But  they  do,  and  we  breathe  easier. 

In  one  red  blood-cell  are  unnumbered  millions  of  millions 
of  molecules  of  hemoglobin.  Each  molecule  is  of  huge  size 
and  of  such  complexity  as  to  baffle  the  imagination.  Here 
is  its  supposed  molecular  formula:  C758Hi203Ni95S3FeO2i8; 
molecular  weight,  16,669.  Only  three  atoms  of  sulphur,  one 
of  iron.  But  iron  is  iron  and  a  little  of  it  goes  a  long  way 
in  the  affairs  of  life — and  leads  to  some  amazing  perform- 

Most  of  hemoglobin  is  globin,  a  protein,  as  might  be 
inferred  from  the  nitrogen  and  sulphur  in  the  molecule.  The 
remaining  5  per  cent  is  iron  salts  or  hematin  with  a  com- 
paratively simple  molecular  formula  of  G34H34N4Fe05.  That 



hematin  will  crystallize  we  have  seen ;  the  crystals  themselves 
are  as  specific  for  species  as  are  starch  grains.  A  horse's 
hemoglobin  crystal  no  more  looks  like  that  of  a  human  being 
than  a  man  looks  like  a  horse;  but  a  mule's  crystal  is  half- 
way between  that  of  a  donkey  and  a  horse.  Why  not?  There 
are  such  relationships  as  blood. 

Blood  is  blood  and  that  of  all  mammals  has  the  same 
constituents  in  about  the  same  proportions.  Yet  blood  is 
specific  for  different  species,  and  the  amount  of  difference 
suffices  to  prove  that  man  is  closer  blood  kin  to  Old  than  to 
New  World  monkeys.  By  means  of  a  blood  test  it  was 
proved  that  the  malaria-carrying  mosquito  feeds  on  pigs  and 
cattle  as  well  as  on  man;  by  that  test  horse-meat  has  been 
distinguished  from  beef;  blood  on  a  cleaver  proved  to  be 
deer's  blood,  and  not  wild  duck's,  as  the  man  accused  of 
poaching  swore  it  was;  and  a  stain  was  proved  to  be  human 
blood  after  a  lapse  of  sixty-six  years. 

All  of  which  opens  up  a  large  vein  in  life — ranging  from 
murder  trials  to  immunity  from  bacteria. 

Any  foreign  protein  element  in  a  blood-stream  is  a  foreign 
body,  an  antigen.  An  antigen  will  provoke  an  antibody.  A 
foreign  red  blood-cell  is  an  antigen;  the  antibody  it  provokes 
is  a  hemolytic,  a  dissolver  of  foreign  red  blood-cells.  Bac- 
teria in  a  blood-stream  are  antigens;  the  blood's  reply  is 
four  kinds  of  antibodies:  opsonin,  makes  them  tasty  to  the 
phagocytes;  agglutinin,  causes  them  to  herd  together  and 
consequently  likely  to  be  engulfed  in  lots;  precipitin,  causes 
them  to  settle  down  or  precipitate  when  held  in  solution; 
and  lysin,  which  dissolves  bacteria.  Lysins,  opsonins, 
agglutinins,  precipitins,  etc.,  are  specific  antibodies,  chem- 
ical systems  which  induce  specific  reactions.  When  bacteria 
are  agglutinated,  thinks  Jordan,  their  negative  charge  of 
electricity  is  reduced;  they  are  thereby  more  subject  to  the 
precipitating  action  of  salts.  The  net  result  of  the  action  of 
the  antibodies  is  to  destroy  the  antigens  or  so  alter  their 



nature  that  they  are  more  easily  handled  by  the  phagocytes, 
or  police  of  the  blood. 

Bacteria,  red  blood-cells,  spermatozoa,  even  pepsin, 
injected  into  the  blood-stream,  evoke  specific  antibodies;  one 
kills  the  bacteria,  one  dissolves  red  blood-cells,  one  disinte- 
grates spermatozoa,  one  neutralizes  the  enzyme  pepsin.  On 
this  capacity  of  the  blood  (and  of  other  tissues)  to  react  to 
antigens  is  based  the  whole  practice  of  acquiring  immunity 
in  bacterial  diseases  by  the  use  of  cell-dissolving  sera. 

Is  it  human  blood?  If  there  is  enough  of  it  the  question  is 
easily  answered;  injected  into  the  body  of  a  rabbit,  the  rabbit 
dies.  But  suppose  there  is  only  a  drop  of  it,  or  the  decom- 
posed remains  of  one  blood  clot?  The  test  is  simple.  Into 
a  rabbit  or  similar  laboratory  convenience  inject  a  non- 
lethal  dose  of  human  blood  (or  ape's — they  are  so  closely 
related  they  are  almost  twins).  The  rabbit's  blood  develops 
a  specific  antigen  for  human  red  blood-cells — it  is  immune 
against  human  blood.  To  some  of  this  rabbit's  immune 
serum  add  the  "suspect,"  and  incubate;  if  there  is  a  flocculent 
precipitate,  the  suspect  blood  is  human  (or  ape)  blood. 

Is  it  blood?  There  may  be  only  a  stain  on  the  floor,  a 
shred  of  stained  cloth,  or  perhaps  only  one  drop  of  water 
left  in  the  bottom  of  the  tub  in  which  the  suspected  murderer 
bathed.  Such  tests  for  blood  can  be  made.  They  depend 
on  the  ability  of  an  inconceivably  small  amount  of  hemin 
to  make  itself  known  by  showing  its  specific  color  when  sub- 
mitted to  delicate  chemical  tests. 


Breathing  is  action  in  a  mechanism  and  implies  work;  and 
that  suggests  heat.  Only  at  absolute  zero  do  molecules  cease 
to  vibrate.  They  cannot  vibrate;  they  have  no  heat.  Heat, 
in  other  words,  is  a  form  of  energy.  And  a  thermometer 
is  a  device  for  measuring  its  energy. 

For  example,  the  heat  under  my  tongue  at  this  moment 



suffices  to  expand  mercury  (raise  its  temperature)  until  it 
registers  98.36  degrees.  The  heat  of  the  skin  of  my  hand 
is  not  so  great;  it  would  be  even  less  if  I  were  making  snow- 
balls. But  the  temperature  at  this  moment  of  my  body  in 
general  is  not  far  from  100  degrees;  call  it  100  for  short. 

Heat,  as  we  saw,  can  also  be  measured  in  terms  of  cal- 
ories— one  calorie  being  the  amount  involved  in  raising  the 
temperature  of  about  two  pounds  of  water  about  two  degrees. 
If  my  temperature  is  100  degrees,  my  body  contains  a  certain 
number  of  calories — ^heat  or  energy  units.  Suppose  I  drop 
dead;  my  body  begins  to  cool.  If  it  is  in  a  warm  room  it 
will  lose  550  calories  within  twenty-four  hours;  if  in  a  cold 
room,  1,000  calories.  Where  has  the  heat  gone?  WHiere 
does  the  heat  of  a  red-hot  poker  go?  Same  place.  It  has 
flowed  out,  radiated,  been  conducted.  My  dead  body  in  a 
room  with  a  temperature  of  100  degrees  would  lose  no 
calories — there  could  be  no  flow  of  heat,  because  heat  flows 
only  from  a  region  of  high  to  a  region  of  low  temperature. 
But  suppose  I  am  not  dead  yet,  but  have  only  lost  a  leg; 
my  temperature  remains  about  the  same,  but  I  have  dimin- 
ished the  calories  in  my  body — I  have  less  body.  Heat 
would  still  be  conducted  from  my  body;  there  would  not  be 
so  much  heat  to  conduct. 

Heat,  being  a  form  of  energy,  does  things,  causes  change — 
a  rise  in  temperature,  a  change  in  state,  a  chemical  change, 
etc.  If  I  apply  enough  heat  to  a  piece  of  coal,  its  carbon 
finally  combines  with  the  oxygen  of  the  air:  it  burns;  I  need 
apply  no  more  heat — the  heat  developed  by  the  oxidation  of 
the  carbon  will  suffice  to  continue  the  reaction  until  the  carbon 
is  all  oxidized. 

Our  daily  intake  of  fuel-food  is,  let  us  say,  2,500  calories. 
Assuming  that  we  are  not  taking  on  fat,  but  just  holding  our 
own,  what  becomes  of  these  2,500  calories?  If  at  the  end 
of  the  twenty-four  hours  we  have  neither  gained  nor  lost 
weight,  and  have  added  2,500  heat  units  to  a  body  already 
at  a  temperature  of  100  degrees  and  it  is  still  at  that  same 



temperature,  these  ingested  calories  must  be  somewhere — 
and  they  cannot  be  inside  us.  We  lose  them  in  two  ways: 
radiation  and  conduction  from  the  skin,  about  73  per  cent, 
or  1,795  calories;  through  loss  of  materials  from  our  body, 
about  27  per  cent,  or  705  calories.  Whatever  leaves  our 
body  carries  with  it  body-temperature  heat.  Thus  through 
saliva,  excreta,  etc.,  we  lose  about  50  calories;  through 
expired  air,  about  265  calories;  and  by  sweat,  about  365 
calories.  These  are  all  heat  losses,  means  of  ridding  the 
body  of  the  heat  liberated  in  the  2,500  calories  of  ingested 

All  this  is  simple  enough.  It  is  equally  obvious  that 
engines  work  best  under  certain  temperature  conditions. 
Motor  engines  must  be  protected  from  too  great  heat  by 
cooling  devices,  airplane  engines  from  too  great  cold  by 
heating  devices.  A  big  tree  will  sweat  a  half -ton  of  water 
on  a  hot  day  to  keep  its  temperature  down.  Our  body  engine 
will  not  work  at  all  if  our  temperature  varies  a  few  degrees 
from  normal.  We  freeze  to  death  when  we  cannot  make 
enough  heat,  and  die  of  fever  or  sunstroke  when  we  cannot 
get  rid  of  enough  heat.  At  105  degrees  enzyme  action 
ceases  through  autodestruction,  the  brain  engine  cannot  work; 
above  105  degrees,  the  brain  begins  to  be  destroyed. 

Which  means  that  our  body  functions  best  at  a  certain 
average  temperature.  When  our  temperature  varies  more 
than  2.5  degrees  from  that  normal  average,  our  oxygen 
metabolism  is  upset  and  our  body  is  abnormal.  We  birds 
and  mammals  are  not  so  much  warm-h\oode6.  animals  as  we 
are  constant-lem^exdiXme  animals. 

How  does  our  body  so  regulate  its  heat  production  and  its 
heat  loss  that  its  vital  parts  are  kept  at  a  practically  constant 
temperature?  It  is  easy  enough  to  see  how  ingesting  more 
calories,  taking  more  exercise  and  consequent  burning  of 
stored  calories,  and  clothing  keep  us  warm  even  though  we 
are  breathing  the  frosty  air  of  40  below  zero;  but  how  do 



we  keep  cool  when  the  thermometer  stands  at  120 — as  they 
do  in  Death  Valley? 

Simply  by  getting  rid  of  more  heat. 

Heat  loss  through  expired  air  is  fairly  constant  and  little 
subject  to  change  in  outside  temperature.  Expired  air  is 
always  warmer  than  inspired  air;  it  is  almost  saturated  with 
vapor.  We  expire  about  a  pint  of  water  a  day;  each  gram 
of  water  vaporized  required  one-half  of  a  calorie,  180  in  all. 
To  warm  the  inspired  air  consumed  85  calories. 

The  blood  is  the  go-between  for  all  parts  of  the  body. 
Heat  generated  in  any  part  of  the  body  will  heat  the  blood 
that  passes  by.  The  water  in  the  blood  is  the  transporter  and 
distributor  of  heat.  But  the  blood  also  reaches  about  sixteen 
square  feet  of  skin  and  about  ninety  square  yards  of  lung 
lining.  In  both  skin  and  lungs  it  comes  close  to  outdoor 
temperature.  Through  the  vasomotor  nerves  the  supply  of 
blood  to  the  skin  is  under  automatic  reflex  control.  The 
vasomotor  system,  then,  is  the  principal  regulating  mecha- 
nism. In  air  close  to  body  temperature  there  can  be  but 
little  loss  of  heat  from  skin  by  radiation  and  conduction; 
in  cold  atmosphere  the  loss  will  be  excessive.  The  vasomotor 
system  must  arrange  for  compensation.  The  details  are  not 
yet  known,  but  the  results  can  be  seen. 

Sweat,  for  example.  We  have  about  2,000,000  tiny  pores, 
or  sweat-glands,  in  our  skin,  about  500  to  the  square  inch, 
about  2,000  per  square  inch  in  the  palms  of  our  hands  and 
the  soles  of  our  feet.  Sweat  is  99  per  cent  water,  1  per  cent 
salt,  a  small  portion  being  urea.  An  average  man  on  a 
mild  summer  day  will  sweat  about  two  pints.  He  can  sweat 
as  much  as  ten  pints;  in  that  case  10  per  cent  of  his  urea 
excretion  would  pass  out  through  the  sweat-glands. 

Cats  and  dogs  do  most  of  their  sweating  through  pads  on 
their  feet.  A  dog  also  opens  his  mouth  wide  and  sweat — 
in  the  form  of  saliva — drips  from  his  outstretched  tongue. 
Both  dog  and  man  also  pant,  thereby  increasing  lung  ventila- 
tion.   If  the  outside  humidity  is  not  great,  panting  increases 



the  amount  of  evaporation  of  water  from  the  blood  in  the 

In  the  dry  air  of  Death  Valley  deserts,  with  the  temperature 
at  120,  we  do  not  "sweat  a  drop."  We  do;  the  sweat  evap- 
orates as  fast  as  it  is  secreted.  On  hot,  moist  days  it 
evaporates  slowly  because  air  can  only  take  up  so  much 
moisture.  Moist  air  itself  is  a  fine  conductor  of  heat.  Hence 
more  sunstroke  with  moderate  heat  and  great  humidity  than 
with  great  heat  and  slight  humidity. 

Sweating,  then,  is  an  active  transfer  of  fluid  from  inside 
the  body  to  the  surface  of  the  body,  where  it  is  vaporized, 
a  heat-consuming  process.  The  sweat  that  is  not  vaporized 
drips  from  the  skin,  but,  as  Du  Bois  points  out,  it  "removes 
no  heat  from  the  body  except  as  it  diminishes  the  weight 
of  the  body."  Sweating  is  a  different  matter  from  the  mere 
evaporation  of  water  from  a  non-sweating  skin. 

When  air  temperature  reaches  86  or  more,  or  when  ordi- 
nary vaporization  from  lungs  and  skin  and  the  amount  which 
can  be  lost  by  radiation  and  conduction  falls  below  the 
amount  of  heat  that  must  be  eliminated,  the  sweat-glands 
begin  to  pour  out  water.  Actual  sweat  is  the  body's  last 
resort  in  keeping  down  the  temperature.  A  flushed  face 
covered  with  sweat  is  a  skin  losing  hot  water  because  it  cannot 
lose  steam  fast  enough.  Usually  our  skin  is  "slightly  moist, 
moister  than  a  dead  animal,  not  as  moist  as  meat  in  a  butcher 

The  actual  secretion  of  sweat  is  controlled  by  sweat  nerves. 
The  secretion  itself  increases  the  heat  loss.  Rarely  individ- 
uals are  found  without  sweat-glands — icthyosis  hysterix. 
They  cannot  work  in  summer  or  in  heat  where  a  normal  man 
would  sweat.  In  one  well-known  case  even  slight  work  would 
send  the  individual's  temperature  up  to  105  degrees. 

There  is  always  blood  in  the  skin.  On  warm  days  the 
capillaries  are  gorged  with  blood;  if  the  air  is  not  too  hot, 
much  heat  is  lost  by  radiation  and  conduction  and  by  vapori- 
zation.   On  cold  days  the  blood  is  withdrawn  from  the  skin; 



as  Du  Bois  says,  we  change  our  skin  into  a  suit  of  clothes 
and  withdraw  the  zone  where  the  blood  is  cooled  to  a  level 
some  distance  below  the  surface. 

This  change  in  volume  (and  possibly  in  concentration)  of 
peripheral  blood  is  a  matter  of  vasomotor  function,  but  what 
part  the  hot  and  cold  points  in  our  skin  play  is  not  yet  known. 
When  air  below  60  degrees  strikes  an  unprotected  body,  the 
cold  points  are  stimulated.  They  tell  the  muscles  to  shiver; 
that  is  their  way  of  getting  warm.  Shivering  is  a  heat- 
producing  device.  Presumably  the  blood  itself  has  become 
more  concentrated,  water  has  been  withdrawn;  it  is 
"thicker" — less  heat  is  carried  to  the  radiating  surfaces.  A 
man  up  to  his  neck  in  a  bath  of  104  degrees  stops  sweating 
on  his  forehead  as  soon  as  one  hand  is  plunged  in  cold 
water.  Same  reason.  Sweat-gland  nerves  also  work  accord- 
ing to  temperature  stimuli.  The  cold  point  nerves  now  cry 
louder  than  the  hot  point. 

Heat  production  is  a  chemical  regulation — action  in 
neuromuscular  system,  action  of  food  on  metabolism;  heat 
loss  is  physical  regulation — sweat  centers  and  nerves,  vaso- 
motor center  and  nerves,  respiratory  center,  water-content  of 
the  blood.  So  marvelously  do  these  mechanisms  work  in 
harmony,  and  so  wonderfully  are  they  co-ordinated,  that 
Howell  believes  it  necessary  to  assume  the  existence  of  a  heat- 
regulating  center  in  the  brain.  WHiere  it  is  and  how  it  works, 
if  there  is  such  a  center,  are  not  yet  known.  It  is  assumed 
that  that  center  is  upset  during  fever. 

Temperature  above  normal  not  caused  by  food,  work,  or 
outside  temperature,  is  fever.  The  cause  of  fever  is  not 

We  sometimes  shiver  during  a  fever.  Fever  disturbs  the 
vasomotor  system;  the  blood  supply  to  the  skin  is  reduced. 
This  makes  the  skin  cool.  Its  "cold  points"  are  stimulated. 
The  blood  concentration  is  increased;  this  may  be  useful  in 
overcoming  the  effects  of  toxins  in  the  body.  A  rise  of  two 
degrees  of  temperature  in  one  hour  means  an  increase  of 



fifty-eight  surplus  calories  stored  in  the  body.  The  body, 
as  Du  Bois  puts  it,  has  become  a  reservoir  in  which  extra 
heat  is  stored;  it  is  released  when  the  temperature  of  the 
body  falls  two  degrees. 

Subnormal  temperature  accompanies  starvation;  less  heat 
produced  because  less  oxidation.  The  body  has  run  out  of 
good  fuel;  it  begins  to  burn  itself;  its  proteins  are  not  good 
fuel,  they  do  not  oxidize  well.  First  to  go  are  the  glycogen 
deposits,  next  the  stored  fats.  Intestine,  lungs,  pancreas, 
brain  and  spinal  cord,  and  heart,  go  last  of  all,  and  in  the 
order  named.  Heart  last  of  all.  Even  the  liver  is  of  little 
use  to  a  starving  man  but  as  firewood;  half  of  it  is  burned 
up  before  the  heart  has  contributed  more  than  2  per  cent  of 
itself  to  the  smoldering  flame.  Twenty-five  per  cent  of  the 
blood  of  the  body  may  be  found  in  a  normal  liver;  its  activity 
releases  much  energy,  it  is  a  reservoir  of  heat.  But  robbed 
of  its  materials,  it  is  an  idle  shop.  The  starving  body  burns 
it  to  keep  the  brain  and  heart  warm.  In  all  the  world  of 
warm  blood  there  is  nothing  so  dead  as  a  cold  heart. 


Glands  are  no  more  unique  in  life  than  any  other  structure 
or  organ  evolved  for  living  purposes.  We  find  no  glands 
in  an  ameba,  but  the  ameba  has  a  full  set  of  test  tubes  for 
chemical  reactions.  At  any  rate,  it  oxidizes  carbon  for  vital 
purposes  and  synthesizes  dead  into  living  protoplasm.  A 
cow  also  does  that,  and  manages  to  get  most  of  the  neces- 
sities of  life  into  her  milk;  her  milk  will  rear  a  calf. 

Her  body  and  ours  are  organic  wholes,  held  together  for 
reaction  purposes  by  a  nervous  system,  held  together  for 
growing  and  living  purposes  by  the  blood.  Into  that  blood 
all  the  cells  of  the  body  dip  their  fingers  for  what  they 
require;  into  it  they  dump  what  they  do  not  require  or  what 
they  have  made  that  other  parts  of  the  body  may  require. 
So  it  comes  about  that  certain  groups  of  cells  are  organized 



to  clear  the  blood  of  refuse,  other  groups  to  deliver  to  the 
blood  or  to  the  alimentary  canal  chemical  reagents,  enzymes, 
and  regulators. 

These  special  groups  of  cells  are  called  glands — Latin  for 
acorn.  Any  organ  in  the  body  which  secretes  something  the 
body  needs,  or  excretes  waste  which  otherwise  would  be 
injurious  to  the  body,  is  a  gland.  I  keep  moving  my  elbow; 
it  does  not  wear  out;  certain  glands  secrete  elbow  oil.  Bones, 
muscles,  organs,  all  contribute  to,  all  benefit  by,  the  scheme 
of  the  secretions  of  glands. 

Our  body  contains  literally  millions  of  glands.  Some  are 
endlessly  duplicated — sweat,  oil,  and  intestinal  glands; 
others  are  single  or  in  pairs.  Some  always  work;  others 
work  only  part  time.  Some  function  only  for  a  certain  period 
during  life  and  then  slink  away,  like  actors  who  appear  dur- 
ing one  scene  only.  Some  serve  a  double  function,  like  the 
liver  and  the  glands  of  reproduction.  Some  secrete  definitely 
known  substances;  others  have  no  known  secretion.  Some 
have  a  canal  or  duct  by  which  their  secretions  are  delivered 
to  definite  organs;  others  are  ductless. 

Our  skin  is  thickset  with  two  kinds  of  glands  which  have 
ducts  or  canals.  About  2,000,000  sweat  glands  secrete 
water  and  so  help  to  regulate  our  temperature.  Fat  or 
sebaceous  glands,  usually  one  for  each  hair,  help  to  protect 
the  body  from  cold  and  the  hair  from  becoming  brittle. 

Lachrymal  glands  secrete  tears  through  ducts  which  wash 
and  lubricate  the  eyes.  A  duct  on  the  inner  corner  of  the 
eye  drains  the  dirt-laden  tears  into  the  nose,  if  not  secreted 
too  fast;  then  they  spill  over  the  eyelids. 

Our  alimentary  canal  is  beset  with  food-digestion  glands. 
Parotids  in  the  cheek,  sub-linguals  at  the  base  of  the  tongue, 
and  sub-maxillaries  in  the  lower  jaw,  "make  our  mouth 
water,"  preparing  food  for  digestion  and  acting  as  a  ferment 
to  convert  starch  into  sugar.  The  big  glands  of  food  digestion 
are  the  gastric  glands,  pancreas,  and  liver.  The  pancreas 
secretes  ferments  that  digest  fats,  carbohydrates,  and  pro- 



teins.  The  liver,  largest  of  our  glands,  secretes  bile,  forms 
urea,  and  stores  glycogen. 

The  secretions  of  all  these  glands  are  carried  by  ducts  to 
other  organs  or  systems.  They  are  known  as  the  duct,  or 
exocrine,  glands.  They  deal  with  the  upkeep  of  the  indi- 
vidual. On  their  proper  functioning  depend  in  general  food 
digestion  and  the  protection  of  the  body  from  extremes  of 
temperature  and  of  the  eyes  from  motes.  But  there  is  an 
important  difference  between  the  glands  of  food  digestion 
and  the  glands  which  water  the  eyes,  oil  the  skin,  lubricate 
the  joints,  and  regulate  the  temperature.  Food-digestion 
glands  secrete  definite  chemical  substances,  manufactured 
within  the  glands  themselves. 

Some  of  these  chemicals  are  manufactured  in  large  quan- 
tities— ^hydrochloric  acid,  for  example,  by  the  stomach. 
Other  chemicals  are  produced  in  amounts  so  small  that  they 
are  only  with  difficulty  discovered  by  the  physiologist;  such 
are  the  enzymes.  These  chemicals  are  prepared  by  the 
glands  from  the  nutrient  solutions  carried  to  them  by  the 
blood.  It  is  their  business  to  pick  them  out  and  combine 
them  into  such  products  as  in  the  course  of  evolution  they 
have  become  adapted  to  produce.  They  must  be  plentifully 
supplied  with  arterial  blood. 

The  primary  function  of  the  duct  glands,  then,  is  to  keep 
the  body  fit  and  to  supply  it  with  tools  for  razing  dead 
bodies  so  that  their  debris  may  be  built  into  living  bodies. 
To  that  extent  they  are  concerned  in  growth  and  the  proper 
functioning  of  the  body  mechanism.  But  the  control  of 
growth  itself  and  the  determination  of  the  character  of  the 
body  mechanism  depend  on  other  glands — the  endocrines — 
whose  nature  until  recently  was  not  even  suspected. 

The  kidneys  are  not  glands  of  secretion;  they  secrete 
nothing.  They  are  excretory  organs.  Their  function  is  to 
filter  from  the  500  quarts  of  blood  which  flows  through  them 
every  twenty-four  hours,  poisonous  nitrogenous  wastes,  salts, 
and  enough  water  to  carry  them  in  solution  through  the 



ureters  to  the  bladder.  The  kidneys  are  indirectly  con- 
trolled by  the  vasomotor  nerves,  more  directly  by  chemical 
stimuli  in  the  blood  itself.  Increase  of  oxygen  to  the 
kidneys,  for  example,  decreases  urine  secretion.  Substances 
such  as  urea  are  always  filtered  out  of  the  blood  by  a  normal 
kidney,  but  sugar,  chlorides,  and  sodium  are  excreted  only 
when  the  blood  carries  them  in  excess.  In  diseased  kidneys 
the  sensitive  filtering  membrane  is  damaged,  and  thus  often 
valuable  elements  are  filtered  out  from  the  blood  to  the 
detriment  of  the  body. 

Abel  believes  that  possibly  his  false  kidney,  by  which  he 
has  filtered  out  red  blood-cells,  can  be  so  perfected  that  the 
blood  of  the  human  body  might  be  forced  to  pass  through 
it,  filtering  out  such  poisons  as,  for  example,  corrosive  sub- 
limate, which  the  kidneys  themselves  cannot  remove,  and 
other  poisons  which  because  of  temporary  kidney  breakdown 
cannot  be  eliminated. 


The  little  fleas  which  us  do  tease 

Have  other  fleas  to  bite  'em, 
And  these  in  turn  have  other  fleas, 

And  so  ....  ad  infinitum. 

"Flea"  is  any  animal  that  lives  on  or  within  the  body  of  a 
host  and  depends  on  that  host  for  its  food.  All  such  are 
parasites.  Eccles  claims  that  half  of  all  the  animals  in  the 
world  are  parasites. 

The  most  numerous  and  deadly  parasites  come  from  that 
great  half -animal,  half-plant  underworld  known  as  bacteria. 
Second  only  in  deadliness  are  some  of  the  unicellular  organ- 
isms of  the  animal  world,  the  Protozoa.  More  annoying,  but 
of  quite  a  different  order  in  their  powers  of  destruction,  are 
some  of  the  lower  members  of  the  Metazoa  subkingdom. 

To  the  extent  that  parasites  live  on  or  within  us  or  find  a 
temporary  home  with  us,  and  to  the  extent  that  they  are  causes 



of  disease  and  death,  they  are  proper  objects  of  our  interest 
and  fit  subjects  for  our  attention.  Indeed,  the  claim  has  been 
made  that  natural  death  in  man  and  higher  animals  is  due  to 
parasitic  organisms.  This  probably  overstates  the  case,  but 
it  is  a  fact  that  micro-organisms  enormously  influenced  or- 
ganic evolution,  that  certain  forms  are  constant  menaces,  and 
that  no  part,  tissue,  or  function  of  our  body  is  germ-proof. 
The  menace  is  great  because  of  their  astounding  capacity  to 
multiply,  constant  because,  like  the  poor,  they  are  always  with 
us.  A  pin-scratch  may  be  as  fatal  as  a  rifle  ball;  careless 
handling  of  milk  may  plague  a  city. 

The  general  problem  of  parasitism  is  complicated.  We 
shall  look  only  at  those  parasites  which  are  prone  to  infest 
the  human  body  and  are  likely  to  cause  disease.  What  are 
they,  how  are  they  carried,  how  do  they  enter  our  body,  what 
damage  or  disease  do  they  cause,  and  how  may  we  be  rid  of 
them  or  acquire  immunity?  The  answers  to  even  these  ques- 
tions are  often  interrelated.  Malaria,  for  example,  is  not  a 
bacterial  disease,  nor  do  we  "catch"  it — it  is  brought  to  us 
by  a  mosquito.  Malaria,  as  a  disease,  is  not  to  be  understood 
without  reference  to  its  carrier  and  without  a  knowledge  of 
the  life  cycle  of  the  germ  which  causes  malaria.  Again,  rats 
are  not  parasites,  yet  some  of  the  deadliest  scourges  of  the 
human  race  are  rat-flea-borne  diseases.  Why  are  the  rats  and 
fleas  immune  to  plague?  And  how  do  they  carry  germs?  The 
venom  of  a  cobra,  the  ricin  of  the  castor  bean,  the  toxin  of 
diphtheria  germs,  are  deadly.  Are  they  related  substances? 
Only  in  their  disruption  of  normal  human  processes  of  living 
and  in  the  similarity  of  the  response  our  bodies  make  to 
such  substances. 

It  is  true  that  no  question  can  be  raised  regarding  any  one 
phase  of  any  human  process  of  living  without  removing  the 
lid  of  all  of  life.  The  intricacy  of  life  in  its  simplest  forms  is 
profound  enough;  it  is  not  simplified  by  the  addition  of  para- 
sites. And  yet  possibly  all  living  processes  in  higher  organ- 
isms are  brought  about  by  aggregates  of  protein  molecules 



which  function  as  micro-organisms.  If  we  only  knew  more 
about  the  protein  molecule! 

We  shall,  for  keen  minds  are  on  its  trail,  and  sooner  or 
later  it  will  yield  its  secret  and  life  will  be  new  again. 

Meanwhile,  there  are  mosquitoes  to  swat.  And  with  them 
we  may  begin  to  call  the  roll  of  our  parasitic  enemies.  Mos- 
quitoes belong  to  Hexapoda  (six-footed)  insects,  the  most 
diversified,  the  most  numerous,  and  for  their  size  the  smartest 
of  all  animals.  Lice,  fleas,  ticks,  bedbugs,  jiggers,  mosqui- 
toes, flies — dozens  of  kinds,  millions  of  each.  And  a  variety 
for  every  plant  and  animal  on  earth  big  enough  to  carry  one. 
They  live  on  us,  they  live  off"  us.  They  give  us  nothing  useful. 
They  irritate  us.  But  they  do  not  kill  us.  We  are  accustomed 
to  them,  "adapted,"  immune. 

That  is  what  immunity  means.  We  are  not  exempt  from 
fleas  or  dozens  of  other  parasites.  Only  immune.  We  can 
stand  them.  The  germ  of  death  or  disease  carried  by  a  para- 
site is  another  matter.    Immunity  may  come  in  many  forms. 

Insects  are  the  highest  animals  which  infest  or  bedevil  the 
human  body.  Lower  in  the  scale  is  a  flatworm,  the  long,  flat 
Taenia,  or  tapeworm.  Its  life  history  is  longer  and  not  at 
all  flat.  Man  gets  it  from  unsalted,  uncooked  pork.  In  his 
alimentary  canal  it  loses  most  of  its  anatomy  and  becomes 
head  and  long  body  of  dozens  of  segments,  each  for  breeding 
purposes  a  complete  male  and  female.  That  is  what  it  is,  a 
series  of  reproductive  units.  It  needs  no  sense  organs,  has 
none;  as  it  feeds  on  predigested  food  it  needs  no  digestive 
apparatus,  has  none.  Its  head  is  a  hook  to  hang  on  by  and 
a  siphon  to  suck  up  food. 

Our  next  lower  animal  parasitic  enemies  are  the  two 
threadworms — ^hookworm,  trichina.  The  trichina  is  well  un- 
derstood and  now  under  control;  we  hear  little  of  it.  The 
hookworm  is  well  understood;  but  people  will  go  barefooted. 

The  trichina  lives  coiled  up  in  its  cyst  within  a  muscle  cell 
— rat,  cat,  dog,  pig,  man.  There  may  be  80,000  cysts  in  one 
ounce  of  ham:  half  males,  half  females.    Eaten  by  man, 



the  cysts  dissolve  in  the  gastric  juice,  the  worms  are  free. 
They  mate.  One  female  produces  1,000  young.  The  young 
break  through  and  settle  down  in  muscle  cells — 100,000,000 
of  them  in  one  dead  man. 

Hookworm  continues  to  claim  its  millions  of  victims  each 
year  simply  because  proper  precautions  are  not  taken  to  break 
the  vicious  circle  of  its  life  cycle.  It  is  another  case  of 
Parasites  Lost  and  Parasites  Regained,  in  the  words  of  a 
Fijian  school  boy  who,  according  to  Dr.  Vincent,  had  heard 
about  hookworms  and  Milton  the  same  day.  Hookworm  eggs 
hatch  in  warm,  moist  soil.  The  tiny  worms  enter  the  skin  of 
the  bare  feet,  are  carried  by  the  blood  to  the  lungs,  where  they 
bore  through  into  the  throat,  and  thence  are  borne  to  the  ali- 
mentary canal,  where  500  or  more  live  parasitic  lives  attached 
to  the  wall  of  the  small  intestine.  Their  millions  of  eggs  are 
returned  to  the  soil  to  begin  other  cycles. 

Lowest  of  real  animals  to  infest  us  are  certain  unicellular 
Protozoa.  One  group,  the  Sporozoa,  is  exclusively  parasitic; 
and  all  are  internal,  hence  often  called  endoparasites.  Some 
abide  in  the  liver,  some  in  the  intestine,  some  in  the  muscles, 
some  in  the  blood  of  their  host.  Some  are  deadly  enemies 
of  the  human  race.  Only  bacteria  are  more  widely  distributed 
and  few  germs  have  more  plagued  the  human  race  than  the 
Sporozoan  Plasmodia  which  cause  malaria.  Of  the  Sarco- 
dina  Protozoa,  only  the  endameba  is  a  real  parasitic  enemy 
and  in  the  tropics  fairly  destructive  by  causing  dysentery. 
A  similar  but  smaller  ameba  makes  its  home  in  our  mouth 
and  is  always  found  in  pyorrhea  (pus-flow)  lesions,  though 
it  is  not  yet  certain  that  it  causes  pyorrhea.  Only  one  genus 
of  Infusoria  is  parasitic  for  man,  causing  diarrhea  and  dysen- 
tery. Of  the  fourth  Protozoan  group,  the  Mastigophora,  only 
the  Trypanosomas  are  parasitic — and  cause  the  deadly  sleep- 
ing-sickness and  allied  diseases. 

Below  the  lowest  animals  and  below  the  lowest  plants  is  that 
half -plant,  half -animal  underworld  of  bacteria.  But  before 
we  turn  to  them,  let  us  see  how  certain  germs  are  carried  by 



animals — flies,  fleas,  rats,  etc.  Incidentally,  we  shall  see  into 
the  breeding  habits  of  certain  germs. 

The  Black  Death  of  1348-49  devastated  a  quarter  of 
Europe,  killed  25,000,000  people,  and  drove  Boccaccio  out- 
side the  v/alls  of  Florence,  where  he  whiled  away  the  time 
writing  the  Decameron.  In  India,  the  pest  bacillus  cost 
6,000,000  lives  in  ten  years.  Almost  all  plague  bacteria  are 
carried  by  animals,  and  are  transmitted  to  man  by  fleas,  lice, 
mosquitoes,  or  other  parasites. 

A  flea  on  a  dying  rat  seeks  a  fresh  victim,  carrying  the  rat's 
plague  germs  with  it.  Any  man  will  do.  The  flea  empties 
its  alimentary  canal,  then  bites;  the  bite  irritates  the  skin,  the 
man  scratches  it — thereby  opening  his  first  line  of  defense  to 
the  enemy!  The  germs  left  behind  by  the  flea  can  now  get 
into  the  blood.  In  the  new  host  they  begin  to  multiply.  An- 
other flea  may  carry  this  tainted  blood  to  another  human 

More  instructive  is  the  propagation  of  malaria,  or  ague. 
When  science  found  out  where  the  mosquito  gets  malaria  and 
why  the  astounding  clock-like  regularity  of  the  paroxysms 
which  wrack  the  bones  with  chills  and  burn  the  body  of  the 
victim  with  fever,  a  long  stride  was  made  in  making  this 
world  safe  for  human  beings. 

Malaria  is  caused  by  three  (possibly  by  four)  varieties 
of  Plasmodia  of  the  unicellular  Sporozoa.  Sporozoa  repro- 
duce by  spores,  hence  the  name.  Ordinarily,  one  cell  or  one 
bacterium  divides  and  becomes  two.  In  reproduction  by 
spores,  one  divides  into  many  tiny  spores,  each  spore  grows 
to  life  size,  and  again  divides  into  spores.  Each  kind  of 
Plasmodium  has  its  own  time  rate  of  reproduction.  The  ague 
paroxysm  coincides  with  this  reproductive  cycle. 

The  true  home  of  Plasmodia  is  human  red  blood-corpus- 
cles. Within,  they  grow  to  maturity  at  the  expense  of  the 
corpuscle.  They  then  begin  to  divide  and  become  a  mulberry- 
shaped  mass  of  small,  glassy,  ameboid  spores.    This  mass 



rends  the  corpuscle  apart.  The  spores  thus  freed  attach 
themselves  to  other  corpuscles  and  begin  a  new  life  cycle. 

The  rending  of  the  corpucles  releases  their  toxic  wastes 
into  the  blood-stream,  hence  the  fever;  their  destruction  of 
the  oxygen-carrying  constituent  of  the  blood  results  in  anemia 
— and  pernicious  at  that,  without  quinine. 

The  estivo-autumnal  or  quotidian  (daily)  Plasmodium 
completes  its  life  cycle  every  twenty-four  hours.  Each  cycle 
releases  from  six  to  eight  spores  or  new  parasites.  It  is  the 
most  pernicious  of  all  forms  of  malaria.  The  tertian  life 
cycle  is  complete  in  forty-eight  hours,  at  which  time  it  is  about 
twice  the  size  of  a  normal  red  blood-corpuscle;  from  twelve 
to  twenty-four  spores  are  released;  the  chill  occurs  every  other 
day.  The  quartan  variety  breaks  from  the  corpuscle  at  the 
end  of  seventy-two  hours,  with  eight  spores  and  the  attendant 
paroxysm;  the  attacks  are  every  third  day. 

In  other  words,  once  any  one  of  the  three  varieties  of 
malaria  germs  has  entered  the  blood-stream,  it  propagates 
itself  by  spores  and  without  sex,  asexually.  The  existence  of 
its  progeny  is  dependent  simply  on  the  supply  of  red  blood- 
corpuscles.  But  how  does  it  get  into  the  blood  in  the  first 

Enter  the  Anopheles  mosquito,  of  which  there  are  several 
varieties.  They  can  generally  be  distinguished  from  mere 
mosquitoes  by  their  approach.  A  mere  mosquito  on  land- 
ing humps  its  back,  but  holds  its  body  parallel  to  the  surface 
on  which  it  lights;  the  Anopheles  lands  with  its  head  down 
and  body  straight  out  at  an  acute  angle  with  the  surface. 
The  mere  mosquito  drills  with  its  head  for  lever;  the  Anoph- 
eles pushes  in  its  siphon  with  its  entire  body. 

It  siphons  up  the  blood  of  an  ague  victim.  Also  minute 
Plasmodia  spores.  These  are  killed  in  the  digestive  juice  of 
mere  mosquitoes,  but  begin  a  sexual  life  cycle  in  the  Anoph- 
eles. In  this  phase  of  development  the  Anopheles  is  the 
true,  man  the  intermediate,  host  of  the  Plasmodia. 

The  spores,  in  the  Anopheles,  develop  into  males  or 



females.  The  males  develop  fine  thread-like  processes.  One 
of  these  enters  a  female  spore,  fertilizes  it.  The  now  "mar- 
ried" spore  enters  the  wall  of  the  mosquito  stomach,  becomes 
encysted,  grows;  the  mosquito's  stomach  looks  as  though 
covered  with  warts.  The  full-grown  "wart"  now  breaks  up 
into  spores,  each  of  which  produces  myriads  of  minute 
thread-like  bodies.  These  are  carried  to  all  parts  of  the 
mosquito's  body,  even  10,000  in  its  salivary  glands. 

The  mosquito  bites  a  human  victim,  discharging  saliva  and 
a  few  thousand  thread-like  spores.  In  man's  blood  they  can 
take  care  of  themselves.  They  enter  an  asexual  cycle.  They 
soon  become  incredibly  numerous.  Assume  that  the  mosquito 
left  only  1,000  spores:  by  the  tenth  day  they  have  become 
100,000,000;  two  days  later,  1,000,000,000.  When  150,- 
000,000  blood-corpuscles  have  been  invaded,  fever  begins. 

There  may  be  double,  even  triple,  infections — ^from  suc- 
cessive infections  of  the  same  type  or  from  infections  of 
two  or  more  types.  Quartan  fever,  for  example,  may  be 
simple,  double,  or  triple.  In  severe  infections  there  may  be 
more  Plasmodia  than  there  are  red  blood-cells. 

The  germs  of  trench  and  typhus  fevers  are  carried  by 
"cooties."  Typhus  fever  alone  killed  120,000  Serbians  dur- 
ing the  war — all  inoculated  by  lice.  Wlien  control  measures 
were  inaugurated,  the  fever  disappeared.  But  true  control 
cannot  come  to  stay  until  the  facts  of  propagation  are  known. 
In  1915  there  were  2,500  cases  of  malaria  in  an  Arkansas 
town;  within  three  years  there  were  73:  reduction  of  97  per 
cent.  Formerly,  yellow  fever  lived  in  the  tropics  and  now 
and  then  visited  our  Southern  ports,  with  great  loss  of  life. 
It  is  almost  forgotten  now.  Controlled  by  controlling  its 
mosquito  carrier.  In  December,  1918,  control  measures 
began  in  Guayaquil,  Ecuador,  with  88  cases;  they  fell  by 
months:  85,  43,  17,  2,  0.    None  since. 

But  many  kinds  of  germs  need  no  lower  animal  agency 
to  help  complete  their  vicious  life  cycle;  mere  human  social 
relations  suffice.   The  very  manner  of  our  living  is  sometimes 



a  factor  in  the  presence  of  germs — and  in  our  susceptibility 
to  their  ravages.  As  Jordan  says,  tuberculosis  is  primarily 
and  chiefly  a  disease  of  men  living  in  houses  and  of  cattle 
kept  in  stables.  A  tubercular  patient  may  expectorate  up  to 
3,000,000,000  tubercle  bacilli  in  one  day;  the  dried  sputum 
in  a  cool,  dark  corner  may  contain  virulent  germs  for  eight 
months.  A  few  drops  of  urine  may  contain  up  to  500,- 
000,000  typhoid  bacilli. 

The  typhoid  bacillus,  for  example,  before  death  overtakes 
its  host,  passes  into  the  body  of  another  victim,  carried  by 
milk,  water,  food,  fingers,  filth,  flies.  If  it  passes  the  acid 
stomach  of  the  new  host,  it  has  a  clear  field  ahead  until  it 
reaches  the  lymph-nodes  of  Peyer  in  the  small  intestine. 
Whether  it  kills  and  so  dies  with  its  host,  or  is  killed  by  the 
leukocytes  in  the  blood,  it  has  already  multiplied  into  an 
army  and  has  already  sent  some  of  its  forces  out  to  find  new 
victims.  The  germs  of  dysentery,  cholera,  etc.,  of  the  ali- 
mentary canal,  have  similar  cycles.  But  they  must  all  be 
carried;  they  no  more  "pass"  from  one  victim  to  another 
without  a  carrier  than  a  letter  crosses  the  sea  without  a  carrier. 

Many  disease-producing  germs  which  make  their  homes  in 
our  nose,  throat,  or  lungs  (germs  of  tuberculosis,  diphtheria, 
pneumonia,  scarlet  fever,  influenza,  measles,  whooping-cough, 
pneumonic  plague,  etc.),  may  be  carried  by  the  air  itself,  and 
generally  are  sneezed  or  coughed  out  to  be  wafted  about 
until  they  find  new  hosts. 

During  the  Spanish  War  there  was  a  case  of  typhoid  for 
every  seven  American  troops,  a  death  for  every  71;  in  the 
World  War,  there  was  one  death  for  every  25,000  American 
troops.  In  the  old  pre-antiseptic  days,  childbed  fever  mowed 
down  motherhood  and  in  many  hospitals  regularly  killed 
practically  all  mothers.  Death  from  childbed  fever  is  now  a 
dark  stain  on  a  hospital's  reputation.  Deaths  from  typhoid 
are  still  too  common. 

The  conquest  of  germ  diseases  has  only  just  begun.  But 
the  start  of  that  conquest  might  have  been  delayed  until  the 



sweet  by-and-by  without  the  discovery  of  the  germs  them- 
selves under  the  microscope. 


In  1683  there  lived  a  curious  Dutchman  who  ground  lenses. 
He  scraped  some  tartar  from  his  teeth,  mixed  it  with  water, 
and  examined  it  under  his  lens.  What  he  saw  was  a  more 
astounding  sight  than  that  which  confronted  Balboa,  who, 
from  his  peak  in  Darien,  saw  a  lot  of  water.  For  ages  man 
had  known  of  the  Pacific  Ocean  and  millions  of  men  had 
sailed  its  deeps;  Leeuwenhoek,  the  Delft  lens-maker,  was  the 
first  human  being  to  see  a  bacterium. 

And  the  world  promptly  forgot  him  and  continued  for  a 
century  and  a  half  to  argue  "spontaneous  generation"  and 
to  exorcise  devils  as  causes  of  disease.  It  remained  for 
Louis  Pasteur  (1822-95)  to  prove  the  part  bacteria  play  in 
decay,  putrefaction,  fermentation,  and  many  other  processes 
until  then  hidden  from  the  ken  of  man.  Koch,  in  1876, 
proved  the  causal  relation  between  the  bacillus  anthracis  and 
the  disease  anthrax,  and  in  1882  invented  the  "solid  culture- 
media"  for  the  study  of  bacteria.  Pasteur  founded  a  new 
science — biology;  Koch  revolutionized  man's  attitude  toward 
the  world  and  gave  the  human  race  its  first  rational  theory 
of  disease. 

The  naming  of  bacteria  is  still  haphazard  and  much  con- 
fusion prevails.  But  bacteriology  is  a  new  science,  its  inherent 
difficulties  have  been  great,  its  progress  marvelous  beyond 
conception  to  the  surgeons  of  Napoleon's  armies,  who  as- 
sumed that  pus  was  the  first  and  necessary  step  toward  recov- 
ery from  a  wound.  Some  bacteria  bear  the  name  of  their 
host,  some  the  name  of  their  discoverer,  some  the  name  of 
the  disease  they  cause.  Some  bear  all  the  traffic  allows — for 
example,  Granulobacillus  saccharo-butyricus  mobilis  non- 

All  bacteria  show  a  fairly  definite  character  and  are  either 



pathogenic  (disease-producing),  zymogenic  (ferment-produc- 
ing), saprophitic  (decay-producing),  or  chromogenic  (color- 
producing).  But  the  line  between  bacteria  which  cause 
disease  and  those  which  do  not  is  far  from  sharp.  Many 
variable  factors  determine  which  bacteria  are  pathogenic, 
when  they  are  pathogenic,  and  for  whom. 

Bacteria  are  so  small  that  almost  nothing  of  their  anatomy 
is  known  but  their  shape,  and  that  changes  according  to 
circumstances.  They  not  only  vary  during  their  life  cycle, 
but  as  individuals;  even  abnormal  and  monstrous  forms  are 

According  to  Jordan,  all  bacteria  are  inclosed  within  a 
cell  wall  or  capsule,  which  looms  up  under  the  microscope 
like  a  halo.  As  this  capsule  is  not  cellulose,  bacteria  are  not 
true  plants.  Which  means  nothing,  for  many  sure  plants  are 
more  like  true  animals  than  they  are  like  true  plants.  It  is 
in  the  nature  of  living  beings  that  there  can  be  no  sharp  line 
between  the  lowest  plants  and  animals. 

According  to  outline,  three  forms  of  bacteria  are  recog- 
nized: rod-shaped,  bacillus;  corkscrew-shaped,  spirillum; 
round-like-a-berry,  coccus.  But  these  names  give  no  clue  to 
their  character;  noxious  and  innoxious  bacteria  are  equally 
indifferent  to  how  they  look  under  the  microscope.  The  cocci 
are  also  called  micrococci  (small  berries).  Some  cocci 
divide  in  one  plane  and  go  in  pairs  like  Damon  and  Pythias, 
or  form  chains,  and  are  called  streptococci;  some  divide  in 
two  planes  and  form  flat  sheets  or  clusters  like  a  bunch  of 
grapes,  and  are  called  staphylococci;  some  divide  in  three 
planes  and  form  cubical  bundles,  and  are  called  sarcinae. 
There  are  also  strepto-bacteria,  traveling  like  chain-gangs. 
But  bacilli  and  spirilla  divide  at  right  angles  to  their  long 
axes  and  generally  lead  detached  lives.  Up  to  1900  there  had 
been  identified  and  named  1,272  genera  of  bacteria,  divided 
as  follows:  bacilli,  833;  cocci,  343;  spirilla,  96. 

Because  rather  sharply  differing  from  both  bacilli  and 
cocci,  Jordan  believes  the  spirilla  group  should  be  put  into 



a  class  by  themselves  and  called  spirochetes  (coil-bristle). 
They  are  long,  spiral,  and  thread-like;  some  ten  times  the 
length  of  a  red  blood-cell.  To  this  group  belong  the  germs 
of  syphilis  (treponema  pallidum),  yellow  fever  (leptospira 
icteroides),  yaws,  infectious  jaundice,  and  relapsing  fever. 

The  average  bacterium  is  about  1 /20,000  of  an  inch  long. 
The  influenza  bacillus  is  about  half  that  size;  the  germ  of 
infantile  paralysis  is  smaller  yet.  One  hundred  thousand 
typhoid  bacilli  could  lie  snug  in  the  space  of  a  match;  15,- 
000,000,000,000  of  them  to  the  ounce!  A  red  blood-cell  is 
pretty  small,  but  it  is  as  big  as  a  pea  when  magnified  by  the 
diameters  necessary  to  raise  an  influenza  germ  to  the  size 
of  a  needle-point.  The  smallest  visible  bacterium  is  18/100,- 
000,000  of  an  inch  in  diameter;  the  ultramicroscopic  or 
filterable  bacteria  (viruses)  are  one-tenth  that  size;  that  is, 
they  are  only  half  the  shortest  wave-length  of  any  visible 
light-ray.  Under  the  ultramicroscope,  such  objects  may  be 
seen,  but  merely  as  luminous  points  without  diff'erence  as  to 
size,  shape,  or  structure.  About  forty  filterable  viruses  are 
known  to  exist,  but  nothing  is  known  of  the  germs  themselves 
except  that  they  pass  through  filters  and  can  be  very  destruc- 
tive. Among  them  are,  presumably,  the  germs  of  smallpox, 
dengue  fever,  trachoma,  infantile  paralysis,  measles,  hy- 
drophobia, influenza,  and  foot-and-mouth  disease. 

All  bacteria  have  some  power  of  locomotion.  The  typhoid 
bacillus  can  make  about  a  tenth  of  an  inch  an  hour,  or  2,000 
times  its  own  length.  Some  travel  faster — so  fast  that  if  we 
could  move  as  fast  in  proportion  to  our  size,  we  could  run  a 
mile  a  minute. 

Bacteria  show  amazing  vital  capacity.  They  can  defy 
hours  of  boiling  water;  their  spores  can  resist  a  temperature 
of  212  degrees.  Some  sulphur  bacteria  haunt  hot  springs  in 
water  at  190  degrees.  Some  multiply  at  freezing  point.  Ty- 
phoid and  diphtheria  germs  will  live  for  days  in  a  tempera- 
ture of  liquid  air  (284  below  zero).    Some  bacteria  have 



been  known  to  defy  liquid  hydrogen  temperature  (464  below 

Even  more  astounding  is  their  capacity  to  multiply.  One 
becomes  two  by  simple  division.  The  germ  of  Asiatic  cholera 
can  divide  every  fifteen  minutes.  Within  twenty-four  hours 
one  could  become  78,700,000,000,000,000,000,000,000,- 
000;  but  the  victim  is  usually  dead  in  less  than  twelve  hours, 
killed  by  the  toxins  of  these  prodigious  workers.  In  grow- 
ing and  dividing,  they  have  consumed  food  and  liberated 
carbon  dioxide.  They  are  foreigners  in  our  system,  living  at 
our  expense  and  leaving  their  toxic  garbage  for  us  to  elim- 

The  air  we  breathe  and  the  food  we  eat  are  full  of  bacteria, 
and  our  body  is  covered  with  them.  This  is  not  literally  true, 
but  it  is  true  enough  to  emphasize  the  question :  why  are  they 
not  always  and  more  promptly  fatal?  Many  factors  enter  into 
the  case.  For  example,  an  entire  group  of  bacteria  live  on 
our  skin,  where  they  are  harmless.  A  scratch  or  a  pinprick 
opens  the  skin.  Now  they  are  inside  our  body,  but  the  only 
damage  may  be  a  boil  or  a  pimple.  Boils  are  usually  not 
contagious  and  rarely  fatal.  Sometimes  they  are.  It  de- 

The  hay  bacillus  is  everywhere;  in  the  air,  water,  soil; 
probably  some  in  the  dust  which  my  eyelids  keep  wiping  from 
my  eyes.  If  I  am  in  a  weakened  or  run-down  condition,  this 
bacillus  may  lead  to  a  serious  infection  in  my  eye.  Ordina- 
rily, nothing  happens.  The  hay  bacillus  is  a  parasite,  at 
home  wherever  it  lands;  it  has  established  equilibrium  with 
its  host.  As  Jordan  says,  the  less  completely  adapted  the 
bacterium  is  to  its  host,  the  more  virulent  the  disease.  Old 
diseases  decrease  in  severity,  increase  in  frequency. 

Hence  the  really  dangerous  pathogenic  bacteria  as  a  rule 
do  their  damage  in  short  time;  they  are  not  adapted  to  live 
in  their  host;  they  kill.  To  kill  the  hand  that  feeds  one  is 
not  biologic  adaptation.  How  and  why  bacteria  injure  us 
are  again  dependent  on  many  factors.   But  we  may  recognize 



two  general  ways:  by  specific  toxins  locally  released  (tox- 
emia); by  invasion  of  blood-stream  or  tissue  and  resultant 
damage  due  to  general  bacterial  activity  (bacteremia). 

Diphtheria  and  tetanus  are  good  examples  of  toxemic  dis- 
eases. They  are  localized;  the  toxin  liberated  is  specific 
and  highly  poisonous.  Syphilis  is  a  good  example  of  a  blood- 
poisoning  disease;  at  first  localized,  the  germs  soon  enter  the 
blood-stream  and  from  the  blood  may  affect  different  tissues 
or  organs.  Pneumonia  and  typhoid  are  tissue  diseases  pri- 
marily, but  the  bacteria  are  present  in  the  blood  also.  Sep- 
ticemia may  be  due  to  other  causes  than  the  invasion  of  the 
blood  by  the  bacteria  of  suppuration. 

What  is  toxin — for  man  or  bacterium?  In  the  body  of  a 
man  or  an  ape  the  bacillus  of  leprosy  finds  food  and  raiment; 
in  the  body  of  a  dog  or  a  cat,  a  tomb.  An  anthrax  bacillus 
will  not  grow  in  a  solution  of  corrosive  sublimate  stronger 
than  one  part  to  300,000;  it  will  not  live  if  the  solution  is 
one  to  1,000.  As  for  bacterial  poisons,  the  only  general  state- 
ment that  can  be  made  is  that  they  are  very  poisonous. 
Tetanus  toxin  is  16  times  more  fatal  than  cobra  venom,  120 
times  more  fatal  than  strychnine.  To  put  it  another  way, 
the  minimal  fatal  dose  of  strychnine  is  thirty  milligrams;  of 
tetanus  toxin,  one-fourth  of  a  milligram. 

Certain  plant  toxins  show  resemblance  to  bacterial  toxins. 
One  gram  of  ricin  (from  the  castor  bean),  properly  diluted, 
contains  lethal  doses  for  one  and  one-half  million  guinea- 
pigs.  Ricin  agglutinates  their  red  blood-cells;  but  first  there 
is  a  period  of  "incubation"  for  the  ricin,  and  an  antibody 
(antiricin)  is  formed.  Such  chemical  behavior  and  physical 
action  of  ricin  are  strikingly  like  those  of  bacteria.  But  this 
gives  us  no  clue  to  the  chemical  structure  of  bacterial  toxins. 
They  are  collodial,  presumably,  and  in  many  respects  suggest 
enzymes  in  their  action.  In  the  fact  that  they  do  evoke  anti- 
bodies (antitoxins)  lies  most  of  the  secret  of  tlieir  control  up 
to  the  present  time. 

Which  brings  us  up  to  immunity.   But  note,  first,  that  there 



are  many  kinds  of  immunity — and  back  of  all  the  same 
principle:  I  am  either  immune  or  I  am  not.  If  I  take  it  or 
catch  it,  I  am  not  immune;  if  I  do  not  take  it  or  catch  it,  I 
am  immune.  But  I  may  go  down  with  it  to-morrow!  In  other 
words,  there  are  variable  factors  which  will  determine  my 
predisposition  to  infection  or  my  power  of  resistance  against 
infection:  age,  hunger,  thirst,  fatigue,  exposure  to  extremes 
of  heat  and  cold,  are  such  variable  factors. 

Even  different  strains  of  bacteria  vary  in  their  intensity: 
diphtheria  and  influenza,  for  example.  There  are  mild  epi- 
demics, there  are  severe  epidemics.  Again,  certain  diseases 
seem  to  predispose  toward  invasion  by  the  germs  of  other 
diseases.  Acute  tuberculosis  may  follow  on  the  heels  of 
measles;  streptococci  may  invade  lungs  already  occupied 
by  tubercular  bacilli.  Typhoid  fever  and  pneumonia,  diph- 
theria and  scarlet  fever,  syphilis  and  gonorrhea,  are  well 
known  combinations  of  diseases. 

Trypanosoma,  the  germ  of  sleeping-sickness,  is  carried  by 
flies  from  animal  to  animal.  The  disease  is  almost  regularly 
fatal;  it  cost  Uganda  200,000  human  lives,  the  Congo  Basin 
500,000.  One  infected  animal  sent  to  the  Transvaal  started 
an  epidemic  among  the  cattle;  15,000  died. 

Why  any  animals  left,  then;  or  any  flies?  The  tsetse  fly 
which  carries  the  trypanosoma  is  immune,  as  are  the  wild 
animals  which  live  in  Central  Africa.  But  let  an  outsider — 
dog,  horse,  man — venture  in!  Outsiders  are  not  immune; 
their  blood  has  no  answer  to  sleeping-sickness;  they  die,  un- 
less they  can  get  Bayer's  "205." 

So  it  was  with  Texas  fever:  the  new  cattle  died.  So  it  was 
when  whites  introduced  such  "simple"  children's  diseases 
as  measles,  croup,  whooping-cough,  to  South  Sea  Islanders 
and  to  American  Indians.  They  were  not  immune.  Their 
bodies  had  not  yet  learned  the  art  of  compounding  anti-toxins 
to  new  toxins.   They  died — "like  flies." 

Which  means  that  immunity  itself  is  a  relative  term.  We 
are  all  susceptible  under  certain  conditions ;  we  all  have  more 



or  less  power  of  resistance.  To  some  bacteria  we  are  natu- 
rally immune;  to  others  we  are  naturally  susceptible.  The 
problem  is  to  acquire  immunity.  How  can  we  get  exemption 
from  disease? 

By  having  smallpox  we  acquire  immunity  from  smallpox; 
also  by  vaccination.  Against  typhoid,  from  plague  and 
Asiatic  cholera,  we  acquire  immunity  by  vaccination  with 
dead  bacteria — "cultures."  With  a  secretion  (or  excretion) 
of  living  bacteria  we  acquire  immunity  from  diphtheria.  In 
other  words,  we  become  actively  immune  by  incorporating  into 
our  body  "live  virulent  bacteria,  less  virulent  bacteria,  dead 
bacteria,  bacterial  secretions,  or  bacterial  products  from 
broken-down  dead  bacteria."  An  anti-bacterial  serum  is  a 
protective;  an  antitoxic  serum  is  a  curative. 

Much  is  known  of  the  "how"  of  immunity,  almost  nothing 
of  the  "why."  But  great  advance  in  the  future  will  come  from 
specific  artificial  remedies — drugs,  chemotherapy.  The  prob- 
lem is  to  find  a  drug  that  will  kill  the  bug  but  not  the  patient 
— "magic  bullets  charmed  to  fly  straight  to  a  specific  objec- 
tive, turning  aside  from  anything  else  in  its  path." 

Quinine  is  specific  death  for  malaria  germs;  ipecacuanha 
for  the  ameba  which  causes  amebic  dysentery.  Possibly 
chaulmoogra  oil  is  a  specific  cure  for  leprosy;  asphenamin 
("606"),  for  syphilis,  relapsing  fever,  and  yaws;  atoxyl,  for 
sleeping  sickness.  The  list  of  specific  cures  is  pitiably  small 
yet.  Bacteriology  is  new,  immunology  is  newer.  Only  re- 
cently have  the  chemotherapists  had  real  targets  to  shoot  at. 
The  problems  which  confront  them  to-day  are  vastly  more 
important  than  the  puny  worlds  Alexander  exhausted  in  his 




1.  Endocrine  Glands  and  Hormones.  2.  The  Thyroid  Gland.  3.  The  Para- 
thyroid and  Thymus  Glands.  4.  The  Adrenal  Glands.  5.  The  Emergency 
Functions  of  the  Adrenals.  6.  The  Pituitary  and  Pineal  Glands.  7.  The 
Pancreas — and  Other  "Sweetbreads."  8.  Introducing  the  Gonads.  9.  The 
Dual  Role  of  the  Gonads.  10.  The  Female  Gonads.  11.  The  Male  Gonads. 
12.  Secondary  Sexual  Characters.  13.  The  More  "Human"  Sex.  14.  Endocrine 
Facts  and  Fancies.  15.  The  Individual  That  Is  Regulated.  16.  "How  Can  a 
Man  Be  Born  When  He  Is  Old?"  17.  One  Good  Defect  Deserves  Another. 
18.  The  Parts  That  Wear  Out  First.  19.  The  Best  Life  Insurance.  20.  Our 
Total  Mileage. 


While  life  remains  in  the  body,  the  duct  glands  furnish 
the  necessary  chemicals  for  heat  and  energy  metabolism  and 
for  the  preparation  of  materials  for  growth  and  repair.  If 
they  fail  to  supply  fuel,  the  body  dies;  if  they  fail  to  furnish 
building  material,  the  body  stops  growing.  Let  us  assume 
that  the  duct  glands  do  not  fail.  It  then  appears  that  the  body 
which  began  as  a  fertilized  ovum  develops  into  a  9-pound 
infant  in  9  months.  Why  does  it  not  develop  into  a  90-pound 
child  in  90  months,  or  a  900-pound  prodigy  in  900  months? 
Even  if  it  only  kept  up  its  first  two  years'  rate-growth,  it  would 
weigh  500  pounds  in  twenty-four  years.  It  does  not  grow  so 
big.  It  stops.  Sometimes  too  soon — it  is  dwarfed;  sometimes 
not  soon  enough — it  is  gigantic,  though  rarely,  if  ever,  sur- 
passing the  nine  feet  three  inches  of  Machnow,  the  Russian. 
But  it  stops.  Why? 

Meanwhile  the  growing  body  keeps  changing  in  size,  shape, 
proportions.  Certain  parts  or  organs  appear  before  others 
start  to  appear.    For  a  while  the  brain  grows  faster  than  the 



motor  mechanism;  at  other  times  the  motor  mechanism  grows 
more  rapidly.  The  teeth  have  their  special  periods  for 
growth.  The  infant's  thigh  bone  at  birth  has  2,000,000 
bone-building  cells.  When  that  bone  is  a  finished  adult 
product  it  contains  over  150,000,000  bone  cells.  Why  stop 
at  so  few?  How  do  the  leg  bones  know  when  to  stop  growing 
longer,  the  skull  bones  to  stop  growing  larger?  Why  does  the 
body  grow  by  fits  and  starts  and  finally  seem  to  be  complete? 
What  regulates  the  growth  of  all  these  parts  and  of  the  body 
as  a  whole? 

Moore  replaced  a  rat's  ovaries  with  the  sex  glands  from 
a  male;  her  body  and  behavior  took  on  decided  male  charac- 
ters. By  the  same  operation  which  converts  the  unruly  bull 
into  a  docile  ox  and  the  stringy  cock  into  a  tender-fleshed 
capon,  the  Sistine  Chapel  in  Rome  up  to  1878  maintained  its 
male  sopranos.  Why  does  the  boy's  voice  begin  to  crack 
and  his  face,  almost  overnight  as  it  were,  begin  to  grow  a 
beard  where  there  was  no  sign  of  one?  Is  sex  also,  like  growth 
and  individuality,  a  whim  of  "heredity,"  or  are  our  sex,  in- 
dividual traits,  and  physical  growth  under  the  control  of 
definite  regulators?  Fifty  years  from  now  we  shall  begin  to 
know  the  details,  but  enough  is  now  known  of  the  ductless 
glands  and  their  secretions  to  open  up  not  only  a  new  chapter 
of  life,  but  new  accounts  with  life.  They  regulate  sex,  rate 
of  growth  of  tissues  and  organs,  and  consequently  physical 

The  secretions  of  the  ductless  glands  are  discharged  direct 
into  the  blood,  hence  they  are  also  called  glands  of  internal 
secretion,  or  endocrines  (endon,  within;  krino,  I  separate). 
There  are  commonly  said  to  be  seven  endocrines  proper:  thy- 
roid, parathyroid,  and  thymus,  in  the  neck;  pituitary  and 
pineal,  in  the  center  of  the  head ;  adrenals  and  spleen,  in  the 
abdomen.  But  it  is  not  yet  proved  that  the  thymus,  pineal, 
and  spleen  are  true  glands.  The  liver,  pancreas,  and  sex 
glands  also  function  as  endocrines. 

Endocrine  secretions  are  chemical  in  nature  and  are  usu- 



ally  called  hormones  (exciters).  They  are  also  called  auta- 
coid  substances:  from  acos,  a  remedy — they  act  like  drugs. 
They  are  drugs,  some  of  them  of  astounding  potency.  In 
fact,  no  man-made  drugs  are  so  powerful  as  some  we  make 
in  our  own  drug-store  glands. 

Mere  regulation  is  not,  of  course,  confined  to  the  secretions 
of  glands.  For  example,  the  chief  regulator  of  the  respira- 
tory system  is  carbon  dioxide,  given  off  by  every  cell  of  our 
body;  thus  liberated,  it  functions  as  a  hormone  or  "exciter." 
But,  as  Abel  puts  it,  the  hormones  actually  known  are  definite 
and  specifically  acting  indispensable  chemical  products  which 
modify  development  and  growth  of  other  organs,  especially 
during  embryonic  life,  and  the  entire  metabolism,  including 
that  of  the  nervous  system,  during  adult  life.  Then,  too, 
there  is  a  collective  operation  of  the  endocrines,  as  yet  not 
definitely  known,  but  summarized  by  Barker  as  follows: 

More  and  more  we  are  forced  to  realize  that  the  general  form 
and  the  external  appearance  of  the  human  body  depends  to  a 
large  extent  upon  their  functioning.  Our  stature,  the  kinds  of 
faces  we  have,  the  length  of  our  arms  and  legs,  the  shape  of  the 
pelvis,  the  color  and  consistency  of  our  integument,  the  quantity 
and  regional  location  of  our  fat,  the  amount  and  distribution  of 
hair  on  our  bodies,  the  tonicity  of  our  muscles,  the  sound  of  the 
voice  and  the  size  of  the  larynx,  the  emotions  to  which  our  "ex- 
terieur"  gives  expression — all  are  to  a  certain  extent  conditioned 
by  the  productivity  of  our  hormonopoietic  glands.  We  are,  in  a 
sense,  the  beneficiaries  and  the  victims  of  the  chemical  correlations 
of  our  endocrine  organs. 

In  short,  as  the  discovery  of  enzymes  and  antibodies  gave 
a  new  insight  into  the  problem  of  the  nature  of  living  proc- 
esses, the  discovery  of  the  hormones  opens  up  anew  the  whole 
conception  of  heredity.  We  can  now  say  that  men  are  alike 
because  they  inherit  the  same  kind  of  blood  and  similar  sets 
of  glands  to  secrete  hormones  for  the  blood  to  carry;  but  that 
men  differ  because  they  do  not  meet  the  same  physical  and 
chemical  conditions  during  life  and  as  a  consequence  do  not 



develop  the  same  catalyzers,  the  same  immunity  agents,  or 
the  same  regulating  agents. 

Or  we  can  say,  with  Loeb,  that  the  organism  itself  molds 
itself  into  an  organic  whole;  in  the  case  of  the  human  ovum, 
into  a  human  being,  because  the  genus  Homo  and  species 
sapiens  inhere  in  the  specific  protein  of  the  human  ovum;  but 
that  the  traits  of  individuality  or  "Mendelian  characters"  are 
determined  by  the  enzymes  regulating  metabolism  and  the 
hormones  in  control  of  growth  and  so  of  personality. 


The  endocrine  gland  best  understood  is  the  thyroid  (shield- 
like) astride  our  Adam's  apple.  It  varies  individually  and 
with  age.  It  is  relatively  largest  in  fetal  life.  At  birth  its 
weight  in  proportion  to  the  entire  body  is  as  1  to  300,  by  the 
third  week  as  1  to  1,160,  and  in  the  adult  as  1  to  1,800. 
It  is  generally  larger  in  women  than  in  men.  Why  this  is  so 
is  not  yet  known. 

The  thyroid  usually  consists  of  two  equally  developed  lobes 
two  inches  long,  an  inch  and  a  quarter  broad.  They  vary 
greatly;  one  lobe  may  be  much  larger  than  the  other,  or  may 
be  quite  absent.  Generally  the  two  lobes  are  connected 
by  an  isthmus;  this  also  varies  in  position  or  may  be  absent. 
There  may  be  accessory  thyroids  down  the  trachea  as  far 
as  the  heart. 

Only  in  higher  fishes  does  the  thyroid  become  a  ductless 
gland,  take  on  new  functions,  and  start  a  new  career.  In 
man,  a  duct  is  sometimes  found  in  the  isthmus — vestige  of 
a  condition  found  in  lowest  fishes,  echo  of  millions  of  years 
ago.    It  is  prone  to  trouble. 

Frogs'  eggs  develop  into  fish-like  tadpoles.  Tadpoles  lose 
their  tails  and  gills,  develop  true  lungs,  and  become  frogs. 
Remove  the  tadpole's  thyroid:  it  never  becomes  a  frog;  it 
remains  a  tadpole  for  life.  Feed  a  tadpole  with  thyroid:  it 
becomes  frog  in  a  hurry,  the  fish  stage  of  its  existence  being 



reduced  from  a  year  to  two  weeks;  but  the  frog  is  only  as  big 
as  a  fly.  Feeding  thyroid  to  tadpoles  evidently  produces  two 
results:  it  hastens  metamorphosis  but  retards  growth. 

Children  with  deficient  thyroids,  through  removal,  atrophy, 
or  injury,  become  heavy-featured,  gibbering,  idiotic  dwarfs 
known  as  cretins;  they  do  not  metamorphose  into  normal 
adults.  Their  skin  is  dry  and  hairless;  their  sex  glands  are 
under-developed;  their  pubic  hair  and  puberty  develop  late 
or  not  at  all;  their  temperature  is  subnormal;  they  are  pot- 
bellied because  their  pelvis  remains  small,  their  limbs  short 
and  thick.  The  corresponding  adult  condition  is  known  as 
myxedema:  white,  hairless,  and  thick,  dry,  rough  skin; 
obesity;  lowered  temperature  and  metabolism;  pulse  slow 
and  weak;  mind  dull. 

These  appalling  results  in  both  children  and  adults  have 
been  corrected  by  feeding  thyroid  extract.  The  changes  thus 
produced  have  been  little  short  of  miraculous.  Cretins  have 
increased  in  stature  several  inches  in  one  year.  The  first 
myxedema  patient  to  be  treated  died  in  1920  after  twenty- 
nine  years  of  good  health  due  to  thyroid  feeding. 

Enlargement  of  the  thyroid  from  whatsoever  cause  is  called 
goiter,  or  Derbyshire  neck.  But  an  over-developed  or  over- 
active thyroid  produces  a  definite  disease  known  as  toxic  or 
exopthalmic  goiter,  or  Graves'  disease.  This  is  characterized 
by  increased  metabolism  and  blood  pressure,  rapid  pulse, 
lax  and  moist  skin,  nervousness,  and  protruding  eyeballs — 
hence  the  name,  "exopthalmic."  The  remedy  is  still  in  the 
hands  of  the  surgeon.  The  cause  and  significance  of  change 
in  the  thyroid  in  toxic  goiter  and  the  cause  of  endemic  goiter 
are  not  yet  understood.  Nor  is  it  understood  why  women  are 
more  prone  to  toxic  goiter  than  men,  the  disproportion  in 
some  localities  being  as  high  as  fifteen  to  one. 

It  is  believed  that  the  activating  principle  of  the  thyroid 
hormone  is  thyroxin,  isolated  by  Kendall  in  1918.  Thyroxin 
is  a  crystalline  compound  of  three  molecules  of  iodine  fixed 



in  a  protein  derivative :  tri-iodo-tri-hydro-oxyindole  propionic 
acid,  or  65  per  cent  of  iodine. 

Only  the  thyroid  secretes  thyroxin,  and  apparently  it  is  the 
iodine  in  thyroxin  that  tells  the  story.  Iodine  is  found  in 
many  seaweeds;  is  three  times  more  abundant  in  codfish  than 
in  human  beings;  is  found  in  traces  in  milk  and  in  drinking 
water;  and  gets  its  name  from  its  violet  (iodes)  color! 

Possibly  no  life  exists  without  iodine.  Certainly  normal 
human  life  is  impossible  without  one  one-hundredth  of  a  grain 
of  thyroxin  a  day.  Three  and  a  half  grains  of  thyroxin  are 
all  that  stands  between  intelligence  and  imbecility.  But, 
there  are,  of  course,  dozens  of  causes  of  subnormal  mentality 
other  than  hypothyroidism. 

No  limit  of  function  can  yet  be  assigned  to  any  one  en- 
docrine, because  they  are  parts  of  an  organic  whole  and  func- 
tion as  parts  of  living  individuals.  So  with  the  thyroid: 
much  is  known,  its  whole  story  is  far  from  known.  But 
from  what  is  known  Hoskins  characterizes  it  as  a  regulator 
of  energy  discharge  to  aid  in  adapting  the  animal  to  its  en- 
vironment. To  Carlson  it  is  a  specific  necessity  for  the 
development  of  the  reproductive  mechanism  in  males  and 
for  the  lunar  cycle  in  adult  females.  Both  views  are  founded 
in  facts  and  are  not  in  conflict. 


Closely  associated  with  the  thyroid  are  two  other  endocrines 
which  develop  in  the  epithelium  of  an  embryonic  branchial 
cleft  or  gill-arch.  Of  these  the  parathyroids  are  so  closely 
associated  in  post-natal  life  in  some  animals  that  it  is  impos- 
sible to  remove  the  thyroids  without  removing  the  parathy- 
roids also.    They  were  only  discovered  in  1880. 

They  are  about  as  big  as  peas  and  are  paired,  generally  two 
on  each  side  and  near  the  thyroids.  They  also  vary  in  num- 
ber, size,  and  position;  they  may  extend  far  down  the  trachea. 
Their  function  is  not  yet  understood,  nor  is  it  yet  known  if 



they  are  glands  of  internal  secretion.  It  is  known  that  death 
follows  their  removal,  generally  in  from  twelve  to  forty-eight 
hours.  Sometimes  recovery  seems  assured,  but  death  has 
only  been  postponed — and  not  beyond  fourteen  days.  Death 
is  accompanied  by  tetany — acute  muscular  convulsions,  and 
not  to  be  confounded  with  tetanus,  or  "lockjaw."  In  some 
cases  the  hair  and  nails  fall  off,  the  teeth  become  loose  and 
shed,  and  cataract  of  the  eye  develops.  Hence  it  is  inferred 
that  they  have  to  do  with  calcium  metabolism.  It  is  claimed 
that  tetany  may  be  cured  by  parathyroid  feeding,  but  Carl- 
son maintains  that  true  tetany  has  not  yet  been  cured  by  this 
method.  Improvement  may  result  from  transplanting  para- 
thyroid from  other  animals,  but  when  all  the  parathyroids 
are  removed  tetany  and  death  follow.  Parathyroid  function 
is  a  condition  of  life. 
What  is  tetany? 

Infantile  tetany  is  called  "fits";  it  is  thought  to  be  due  to 
defective  parathyroids.  The  calcium  metabolism  is  upset: 
bad  bone  growth,  the  teeth  do  not  calcify.  The  phosphate 
metabolism  also  seems  to  be  upset:  not  enough  phosphates  are 
excreted.  Also  a  tendency  to  acidosis  in  the  blood,  probably 
due  to  defective  carbohydrate  metabolism.  A  substance  called 
methylguanidin  appears  in  the  urine  and  blood;  it  is  bad 
poison.  Guanidin  is  also  found  in  decomposing  horseflesh, 
in  culture  of  the  anthrax  bacillus,  etc. 

Guanidin  increases  neuromuscular  excitability:  fits, 
cramps,  tetany  spasms.  A  strychnine  salt  also  does  it.  The 
motor  responses  to  stimuli  are  no  longer  co-ordinated,  but 
become  convulsive — "tetanized."  That  is  why  the  lockjaw 
germ  is  called  the  bacillus  of  tetanus.  With  it  at  work  releas- 
ing its  specific  toxin,  muscles  of  jaws  and  other  skeletal 
muscles  "lock."  Spasms  follow  the  slightest  stimulus.  Possi- 
bly methylguanidin  breaks  down  the  resistance  of  the  synap- 
ses of  the  neuromotor  system — as  strychnine  and  tetanus  toxin 
are  supposed  to. 

We  seem  to  be  far  from  the  parathyroids.   It  is  not  known 



if  they  secrete  a  hormone  or  if  they  are  glands,  but  whatever 
they  are  they  are  vital  structures,  and  certain  death — and 
death  with  certain  accompaniments — follows  their  removal. 
But  Collip  has  recently  reported  that  he  has  prepared  an 
extract  from  animal  parathyroids,  which  he  calls  parathyrin. 
With  this  he  claims  to  control  tetany  in  dogs,  and  to  have 
treated  a  child  in  desperate  condition  with  successful  results. 

No  one  knows  yet  what  constitutes  a  normal  human  para- 
thyroid. There  is  even  more  doubt  as  to  what  is  a  normal 
thymus,  or  whether  it  is  a  gland,  or  what  happens  when  it  is 
removed.  It  lies  just  under  the  upper  end  of  the  breast  bone, 
is  well  developed  in  the  fetus,  better  developed  at  the  age  of 
two,  largest  at  puberty.  It  then  begins  to  lose  its  character 
and  becomes  connective  tissue,  lymphatic  tissue,  and  fat.  But 
this  change  is  delayed  by  castration.  Hence  it  is  assumed 
to  hold  back  the  development  of  the  sex  glands  until  puberty. 
Post-mortem  examination  of  400  idiots  showed  no  thymus  in 
75  per  cent.  Its  removal  in  young  animals  retards  growth 
but  hastens  sexual  development ;  the  sex  glands  remain  weak, 
the  body  flabby  and  dwarfed. 

Riddle  claims  that  the  thymus  lost  its  value  for  man  and 
mammals  when  their  ancestors  began  to  incubate  their  eggs 
within  their  body  and  ceased  laying  them,  as  do  birds  and 
reptiles,  with  albumen  and  shells.  That  was  the  original 
function  of  the  thymus.  Pigeons  whose  thymus  has  been  re- 
moved lay  eggs  without  shells;  but  if  fed  thymus,  will  lay 
normal  eggs  with  shells.  If  your  hens'  eggs  have  .too  little 
albumen  or  a  soft  shell,  feed  your  chickens  dried  thymus  of 
an  ox.  And  thank  the  thymus  because  its  secretions  made  it 
possible  for  our  reptilian  ancestor  to  invent  an  egg  that  could 
evolve  into  a  human  ovum. 


The  adrenals,  or  suprarenals,  get  their  name  from  their 
position  just  above  the  kidneys.    Normally  they  are  of  the 



size  and  shape  of  a  large  bean.  But  they  vary:  one — or,  in 
rare  cases,  both — may  be  absent;  there  may  be  accessory 
adrenals  varying  in  size  from  a  pin  head  to  a  large  pea.  Re- 
moval of  one  adrenal  produces  no  known  result.  Removal 
of  both  is  always  fatal,  often  within  a  few  hours.  When 
death  does  not  follow  their  removal  it  is  because  accessory 
adrenals  are  present  and  can  function. 

The  adrenal  in  some  fishes  is  two  separate  organs.  In  the 
human  embryo  it  begins  as  two;  these  unite  to  form  one  body 
with  two  distinct  parts:  an  outside  cortex,  or  bark,  and  a 
medulla,  or  core,  completely  inclosed  by  the  cortex.  The 
cortex  arises  from  the  middle  germ-layer  and  is  derived  from 
the  Wolffian  body,  which  also  assists  in  the  development  of 
the  urogenital  system.  The  medulla  is  part  of  the  outer  germ- 
layer  and  is  derived  from  the  same  embryonic  tissue  as  is  the 
autonomic  nervous  system;  it  is  largely  composed  of  nerve- 
like tissue.  Its  importance  is  possibly  second  only  to  that  of 
the  brain.  No  other  organ  in  the  body  is  so  well  supplied 
with  blood. 

Removal  of  the  cortex  is  always  followed  by  profound 
prostration,  loss  of  appetite,  apathy,  labored  respiration, 
weak  and  irregular  heart,  paralysis,  and,  within  a  few  hours 
or  days,  death.  Its  secretion  has  not  yet  been  isolated;  it  is 
not  certain  whether  it  is  a  secreting  or  a  detoxicating  organ. 
It  is  a  vital  organ.  It  appears  to  stimulate  sex-gland  growth 
and  bring  on  sexual  maturity.  Its  over-activity,  as,  for  ex- 
ample, when  involved  in  a  tumor,  makes  for  precocious  sexual 
development.  Wlien  it  is  infected,  as  it  sometimes  is  in  tuber- 
culosis, a  disease  results  called  "Addison's,"  from  its  dis- 
coverer in  1855.  This  is  the  only  disease  definitely  known 
to  be  caused  by  insufficient  adrenal  cortex.  It  is  as  yet  in- 
curable and  ends  in  death.  Nor  has  the  attempt  to  overcome 
cortical  deficiency,  due  to  disease  or  removal,  yet  met  with 
success.  Addison's  disease  is  accompanied  by  great  muscular 
weakness,  nervous  depression,  digestive  irritability,  and  such 



increase  in  pigmentation  of  the  skin  that  a  white  skin  looks 
like  bronze. 

The  medulla  of  the  adrenals  is  possibly  more  important 
than  the  cortex.  As  it  cannot  be  removed  without  injury  to 
the  cortex,  it  is  not  yet  certain  that  it  is  a  vital  organ  as  the 
cortex  is  known  to  be.  Adrenin,  the  hormone  of  the  medulla, 
was  the  first  endocrine  secretion  to  be  isolated.  Its  deriva- 
tive was  discovered  by  Abel  in  1897  and  named  "epine- 
phrin" ;  its  pure  form  was  isolated  in  1901  by  both  Takamine 
and  Aldrich.  By  1908  it  was  so  well  understood  that  it  was 
artifically  produced  from  a  coal-tar  derivative.  It  is  now  a 
drug  on  the  market  and  sold  as  epinephrin  or  adrenalin. 
Abel  describes  it  as  a  di-hydroxymethyl-aminoethylol  benzine 
or  an  "aromatic  amino  alcohol."   Here  is  its  formula : 

C6H3(OH)2COCH2Cl  +  NH2CH3  >  C6H3(OH)2.COCH3. 

And  here  is  a  curious  fact.  This  remarkable  drug  is  found 
in  man  in  a  gland  of  internal  secretion.  The  principle  of  this 
drug  is  the  constituent  of  a  gland  of  external  secretion  in  the 
skin  of  a  toad.  That  fact  was  unknown  to  the  New  England 
colonists,  but  Toad  Ointment  was  known.  Abel  quotes  the 

Good-sized  live  toads,  4  in  number;  put  into  boiling  water  and 
cook  very  soft;  then  take  them  out  and  boil  the  water  down  to 
half  pint,  and  add  fresh  churned,  unsalted  butter,  1  pound,  and 
simmer  together;  at  the  last  add  tincture  of  arnica  2  ounces. 

What  was  Toad  Ointment  good  for?  Sprains  and  rheuma- 
tism! The  Chinese  still  treat  or  "cure"  dropsy  with  toad- 
skin  preparations,  as  did  Europe  up  to  1775,  when  it  was 
supplanted  by  digitalis.  But  if  the  colonists  had  persevered 
they  might  have  isolated  from  their  toads,  as  did  Abel,  a 
crystal  composed  of  C18H24O4  and  called  bufagin  (bufo, 
toad)  with  the  property  of  a  powerful  heart  stimulant  and 
thereby  good  for  dropsy.  But  they  could  not  have  derived 
epinephrin  from  their  toads  because  they  did  not  have  die 



right  kind  of  toads.  Epinephrin  is  found  in  the  skin  glands 
of  external  secretion  of  an  Upper  Amazon  toad.  The  secre- 
tion of  these  skin  glands  smeared  on  arrows  makes  a  fine 
poison  for  the  natives,  so  powerful  that  in  a  few  moments  it 
will  kill  a  deer  or  a  jaguar.  The  skin  of  that  Amazon  toad 
contains  both  epinephrin  and  bufagin,  both  powerful  drugs, 
acting  fatally  on  the  heart  and  blood  vessels.  Imagine  what 
happens  to  the  animal  that  eats  that  toad! 

Which  brings  us  back  to  adrenin,  a  powerful  drug,  a  power- 
ful cardio-vascular  stimulant.  Normally  our  blood  contains 
about  eight  milligrams  of  it,  which  means  that  the  proportion 
of  adrenin  to  arterial  blood  is  one  part  to  a  billion.  Admin- 
istered as  one  part  in  twenty  million,  it  acts  on  the  uterus  and 
is  a  useful  drug  in  hemorrhages  following  delivery.  It  in- 
fluences some  tissues  when  diluted  to  one  part  in  100,000,- 
000.  It  depresses  the  intestinal  canal  when  diluted  to  one 
part  in  330,000,000!  What  such  dilution  means  has  been 
worked  out  in  terms  of  street  sprinklers  each  of  625  gallons 
capacity.  A  procession  of  such  sprinklers  twenty  miles  long 
and  200  to  the  mile  would  hold  just  enough  water  to  dilute 
one  ounce  of  adrenin  down  to  one  dose.  Large  doses  are 

Adrenin  is  a  drug,  one  of  the  most  potent  our  body  con- 
cocts. Yet  adrenal  feeding  leads  to  no  known  or  proved  re- 
sults. The  administration  of  the  drug  adrenalin  does  lead 
to  profound  results.  Our  body  blood  contains  this  drug. 
Whether  it  is  made  by  or  excreted  by  the  adrenals  is  still  an 
open  question,  but  that  adrenin  has  specific  action  on  the 
vascular  system,  the  nervous  system,  the  blood,  the  alimentary 
canal,  and  on  sugar  mobilization,  there  is  no  doubt.  Nor 
is  there  any  doubt  that  when  administered  as  a  drug  it  in- 
creases the  action  of  local  anesthetics  by  constricting  the 
blood  vessels,  thus  preventing  local  loss  of  the  anesthetic. 
And  as  this  reduces  the  amount  of  anesthetic  required,  it 
also  reduces  the  amount  of  toxin  danger  from  the  anesthetic. 
It  checks  hemorrhages.    It  allays  the  spasms  of  acute  bron- 



chial  asthma.  It  also  stimulates  weak  hearts  and  fortifies  the 
hearts  of  the  old  and  infirm  against  the  shock  of  operation. 

In  short,  adrenalin  exerts  an  influence  upon  all  smooth 
muscle  enervated  by  fibers  of  the  autonomic  nervous  system. 
That  makes  its  responsibility  enormous,  its  influence  on  hu- 
man destiny  second  to  none. 

What,  then,  is  the  nature  of  this  tiny  but  potent  capsule 
tucked  away  in  the  depths  of  the  abdominal  cavity,  nestling 
above  the  great  excretory  organs  of  the  blood?  Recall  the 
potency  of  a  toad's  bufagin  to  control  the  heart,  the  potency 
of  a  toad's  epinephrin  to  kill  a  strong  animal.  Try  to  picture 
a  molecule  of  human  adrenin  from  the  above  formula. 
Realize  the  close  association  of  the  fundamental  vital  proc- 
esses with  the  autonomic  system.  Is  the  human  adrenal  a 
"brain"  which  takes  charge  of  us  when  we  are  confronted 
by  emergencies  which  mean  life  or  death?  It  may  be  thought 
of  in  that  way. 


In  crises  our  body  goes  on  a  "war  footing" — as  our  country 
did  a  few  years  ago.  Piano  manufacturers  began  to  make 
airplanes.  Artists  turned  from  painting  corset  advertise- 
ments to  camouflaging  battleships.  Our  sugar  rations  were 
cut  that  the  fighters  might  have  enough.  The  entire  plant  of 
the  nation  turned  from  peaceful  pursuits  to  speed  up  the 
fuel  for  the  engines  of  war.   Life  had  become  a  dog-fight. 

Ever  try  to  take  a  bone  from  a  dog?  Or  observe  a  cat 
when  a  dog  suddenly  appears?  Or  a  mother  when  some  one 
injures  her  child?  How  do  you  feel  when  you  are  "horror- 
stricken,"  "sick  with  disgust,"  "paralyzed  with  fear,"  "crazy 
with  pain,"  or  so  mad  you  "choke?"  Tongue  cleaving  to 
the  roof  of  the  mouth,  "cold-sweat,"  pupils  of  the  eyes  dilated, 
pounding  heart,  hurried  breathing,  hair  on  end,  muscles  of 
face  and  especially  of  the  lips  trembling  and  twitching:  such 
are  among  the  obvious  symptoms  of  pain,  of  horror,  of  fear, 



We  recognize  many  emotional  states  and  are  subject  to  them 
in  varying  intensity:  pain,  anger,  fear,  rage,  horror,  sorrow, 
anxiety,  grief,  terror,  disgust.  An  insulting  word  may  liter- 
ally alter  our  entire  nature.  We  feel  these  states ;  we  observe 
the  results  in  others.  What  is  not  so  obvious  is  that  the  body 
itself  often  undergoes  profound  physiological  change. 

The  mechanism  by  which  our  natures  can  be  suddenly 
altered  is  to  be  found  in  the  middle  or  sympathetic  division 
of  the  autonomic  nervous  system  and — according  to  the 
theory — the  secretion  of  the  medulla  of  the  adrenal  gland. 
The  way  these  two  work  together  and  the  striking,  sudden, 
and  far-reaching  consequences  of  their  actions,  form  the  basis 
for  Cannon's  claim  in  1914  that  adrenin  is  nature's  reply  to 
the  crises,  the  unexpected  do-or-die  emergencies  of  living 
animals.  Emotional  behavior  gets  its  kick  from  adrenin. 
With  adrenin  cowards  may  fight  for  their  lives,  brave  men 
may  surpass  themselves,  and  all  of  us  can  run  as  we  never 
ran  before;  or  shed  tears  of  sorrow  over  the  loss  of  friends. 

There  are  three  divisions  of  the  autonomic  nervous  system. 
The  upper,  or  cranial,  is  concerned  with  the  joys  and  sorrows 
of  life.  Its  nerves  conserve  the  body,  building  up  reserves 
and  fortifying  the  body  for  times  of  crises.  By  narrowing 
the  pupils  they  shield  the  eye  from  too  much  light.  By  slow- 
ing the  heartbeat  they  give  the  heart  muscles  longer  periods 
for  rest.  By  causing  the  mouth  to  water  they  set  the  juice 
flowing  and  supply  muscular  tone  for  the  alimentary  canal's 
ceaseless  movements.  The  lower,  or  sacral,  division  covers 
the  emptying  mechanisms  of  large  intestine  and  urogenital 
system;  relief  and  comfort  acts. 

Between  cranial  and  sacral  is  the  sympathetic  division — 
enormously  important.  It  dilates  the  pupils  of  the  eyes,  hur- 
ries up  heartbeat,  stands  hairs  on  end  by  causing  each  smooth 
hair-muscle  to  contract,  opens  sweat  glands  (pouring  out 
excess  heat),  stops  movements  in  stomach  and  intestine,  re- 
leases sugar  (the  best  fighting  fuel)  from  the  liver;  and  re- 
leases adrenin.    The  medulla  of  the  adrenal,  alone  of  all  the 



endocrine  glands,  is  connected  with  the  autonomic  nervous 

Here  is  the  point.  Adrenin  itself,  injected  into  the  blood, 
will  dilate  pupils,  stand  hairs  on  end,  constrict  blood  vessels, 
stop  the  vegetative  activities  in  alimentary  canal,  and  release 
sugar  from  the  liver.  Remove  the  liver  from  the  body,  keep 
it  alive  artificially:  adrenin  will  cause  it  to  release  sugar. 

The  real  business  of  the  adrenal  glands,  according  to  Can- 
non's theory,  is  emergency  function.  When  we  must  fight  or 
run  for  our  lives,  our  body  has  no  time  to  fool  with  a  mouth 
watering  for  its  appetite  or  several  yards  of  alimentary  canal 
activity.  The  test  tubes  for  chemical  action,  and  the  fires  to 
keep  these  actions  going,  must  be  neglected  for  the  moment. 
Their  energy  must  be  made  available  for  action  in  the  big 
striped  muscles  of  the  motor  fighting-or-fleeing  mechanism. 

When  a  joy  is  so  strong  or  a  sorrow  or  a  disgust  so  deep 
that  it  breaks  over  the  threshold  of  the  cranial  division  and 
enters  the  sympathetic,  we  lose  our  appetite:  no  saliva,  no 
gastric  or  pancreatic  juice,  no  movement  in  the  intestine. 
Even  an  empty  stomach  stops  growling  and  holds  its  peace 
when  war  is  on. 

And  war  is  on  when  any  of  life's  instinctive  acts  with 
emotional  trimmings  are  thwarted.  Anger.  The  body  is 
prepared  to  fight.  All  its  life  long  life  has  had  to  know  how 
to  kill,  how  to  avoid  death.  It  has  had  to  learn  to  count  on 
its  muscles  and  its  nerves  when  the  test  comes.  Adrenin  is 
supposed  to  be  the  answer. 

According  to  Cannon's  theory,  adrenin  bucks  us  up.  It 
speeds  up  the  heartbeat.  Draws  blood  from  spleen,  kidneys, 
intestines,  and  other  inhibited  organs  of  the  abdomen — thus 
also  reducing  their  size.  Drives  blood  to  the  skeletal  muscles, 
brain,  and  lungs.  Relaxes  the  smooth  muscles  of  the  tiny 
air  sacs  in  the  lungs,  thus  facilitating  the  exchange  of  carbon 
dioxide  waste  for  the  greater  oxygen  required  in  great  eff'ort. 
Orders  the  liver  to  give  the  blood  more  sugar,  the  optimum 
source  of  nmscle  energy.    Drives  fatigue  from  the  muscles. 



Contracts  the  blood  vessels  of  the  skin  and  makes  the  blood 
coagulate  more  quickly,  so  lessening  our  liability  of  bleeding 
to  death  in  case  of  wound.  Adrenin  wins  battles  and  makes 
men  brave;  lack  of  it  may  make  them  cowards. 

It  has  been  urged  against  Cannon's  hypothesis  that  it  is  not 
yet  conclusively  proved.  What  is  proved  is  that  without 
adrenals — or  accessory  adrenals — no  man  lives ;  with  adrenin 
far-reaching  changes  occur  which,  combined,  transform  the 
vegetation  body  into  a  fighting  machine.  Nor  is  there  any 
doubt  as  to  what  our  emotions  do  to  us.  The  role  that  Gannon 
ascribes  to  the  adrenals  is  reasonable  and  plausible;  it  has 
proved  to  be  a  working  hypothesis  in  biology. 


The  pituitary  gland  is  about  as  big  as  the  tip  of  the  little 
finger,  hangs  from  the  base  of  the  brain  by  a  hollow  stem 
(hence  also  called  the  hypophysis  cerebri),  and  is  housed  in 
a  pocket  of  the  sphenoid  bone  called  the  Turk's  saddle.  It 
is  as  near  the  center  of  the  head  as  it  can  get ;  hence  operation 
on  the  pituitary  is  enormously  difficult.  But  if  the  patient 
— dog  or  man — does  not  die  from  brain  injury,  removal  of 
the  pituitary  itself  is  not  fatal.  It  is  not  a  vital  organ,  but  a 
normal  pituitary  is  essential  to  normal  life. 

The  gland  has  two  lobes,  each  of  different  embryonic  ori- 
gin, and  probably  different  in  function.  The  anterior  lobe 
is  much  the  larger  and  is  an  ectoderm  structure,  arising  as 
a  fold  of  the  lining  of  the  mouth.  Its  structure  is  that  of  a 
gland  and  it  has  a  rich  blood  supply.  It  does  not  remain 
constant  in  size.  It  seems  to  be  associated  with  rate  of  growth 
and  sexual  development.  Its  removal  is  followed  by  many 
symptoms,  but  which  are  due  to  its  removal,  which  to  injuries 
to  the  brain,  is  uncertain.  A  substance  called  tethelin  pre- 
pared from  this  lobe  has  been  used  experimentally  and  other- 
wise, but  no  chemical  individual  has  yet  been  isolated.    It  is 



claimed,  but  not  proved,  that  tethelin  hurries  sexual  maturity 
in  the  young  and  promotes  sex  activity  in  adults. 

The  posterior  lobe  arises  from  the  floor  of  the  third  ven- 
tricle of  the  brain  and  is  largely  nerve  tissue.  For  a  dozen 
years  its  active  principle  was  known  to  science  and  used  as 
an  extract  called  pituitrin  by  physicians  and  surgeons, 
especially  as  a  rival  to  ergot  in  obstetrics.  Used  in  overdoses 
or  at  the  wrong  stage  of  childbirth,  it  caused  several  deaths, 
because  it  can  so  act  on  the  uterus  as  to  tear  it  open. 

Abel  is  convinced  that  the  posterior  lobe  has  only  one 
hormone  and  not  four,  as  had  been  claimed  by  German 
chemists.  From  it  he  has  only  recently  isolated  a  pure  tar- 
trate which  he  characterizes  as  "extraordinarily  potent"  and 
endowed  with  several  different  and  distinct  properties.  It  is 
a  thousand  times  more  powerful  than  any  hitherto  known 
stimulant  for  non-skeletal  muscle  tissue — a  thousand  times 
more  powerful  than  the  "extract"  pituitrin  which,  wrongly 
used,  could  tear  a  uterus  asunder! 

Recall  the  twenty-mile  procession  of  street  sprinklers  re- 
quired to  reduce  an  ounce  of  epinephrin  to  a  test  dose:  to 
reduce  an  equal  amount  of  Abel's  pituitary  hormone  would 
require  not  twenty  miles  of  sprinklers,  but  5,000  miles!  The 
actual  test  was  made  on  a  virgin  guinea-pig's  uterus;  it 
contracted  when  suspended  in  a  solution  of  one  part  hormone 
to  18,750,000,000  parts  water.  Such  facts,  as  Hoskins  says, 
make  endocrinology  kin  to  astronomy. 

This  hormone  acts  on  the  entire  cardio-vascular  apparatus. 
By  restricting  the  small  blood  vessels  it  causes  prolonged  rise 
of  blood  pressure.  It  acts  upon  the  respiration,  causing  a 
rhythmic  increase  of  breathing  up  to  a  certain  degree  of 
rapidity,  then  a  gradual  decrease  again  to  a  temporary  stop- 
page of  breathing. 

When  injected  daily  it  has  proved  a  remarkable  remedy  in 
the  disease  known  as  diabetes  insipidus,  not  to  be  confounded 
with  sugar  or  mellitus  diabetes.  In  the  latter  the  kidneys 
eliminate  sugar  that  belongs  to  the  blood  and  is  needed  by 



the  body.  In  insipidus,  it  is  claimed  the  kidneys  leave  so 
much  sugar  in  the  blood  that  the  body  gets  fat.  But  the 
danger  in  diabetes  insipidus  is  the  excessive  and  uncontroll- 
able elimination  of  water  by  the  kidneys  and  a  consequent 
incessant  thirst. 

"Joe,"  the  fat  boy  of  Pickwick  Papers,  had  a  fat  chest, 
flabby  muscles,  and  sexual  infantilism.  To-day  "Joe"  would 
be  diagnosed  as  dystrophia  adiposogenitalis.  The  anterior 
lobe  of  his  pituitary  was  probably  diseased  and  consequently 

Too  much  activity  in  the  anterior  lobe  in  early  life  is 
believed  but  not  proved  to  lead  to  gigantism,  in  later  life  to 
acromegaly.  There  seems  to  be  no  doubt  that  the  pituitary 
gland  is  closely  related  to  growth,  especially  in  connective 
tissue,  cartilage  and  bone,  and  sex-gland  activity.  But  where 
abnormal  growth  occurs  it  is  rarely  possible  to  say  whether 
it  results  from  specific  activity — too  much  or  too  little — in 
the  gland,  or  from  the  pressure  of  a  tumor  on  or  in  the  gland 
or  on  the  floor  of  the  third  ventricle  of  the  brain.  Other 
glands  than  the  pituitary  may  be  involved  when  the  pituitary 
itself  is  abnormal.  Whether  the  pituitary  was  the  primary  or 
the  secondary  cause  of  the  upset  in  response  to  growth  stimuli 
is  not  yet  known. 

Abnormal  adult  growth  changes  know^n  as  acromegaly  are 
characteristic  and  unmistakable:  enlarged  bones  of  the  head, 
hands,  and  feet,  general  lassitude,  pains  in  the  muscles,  lack 
of  interest,  and  depressed  sex  activity  often  leading  to  im- 
potence or  amenorrhea. 

The  famous  Irish  giant  Magrath  had  a  pituitary  as  big  as 
a  hen's  egg.  His  hands  resembled  shoulders  of  mutton,  his 
lower  jaw  was  a  massive  appendage  to  a  huge  face.  A  dis- 
eased pituitary  in  a  normal  adult  caused  the  face  to  grow 
massive  and  ugly,  with  bulging  masses  about  the  eyes,  the 
nose  huge,  the  lips  thick;  the  chest  huge  and  barrel-shaped; 
the  hands  and  feet  of  enormous  size.  A  dwarf  of  twenty 
years  with  an  under-developed  pituitary  had  the  bones  of  a 



child  a  few  weeks  old.  Another  dwarf  of  mature  years  and 
so  tiny  as  to  have  been  "served"  in  a  pie  at  the  Duke  of  Buck- 
ingham's table  in  honor  of  the  Queen  of  Charles  I,  began  a 
second  period  of  growth.  Some  alteration  in  the  pituitary, 

That  the  pituitary  is  concerned  in  sex  growth  is  inferred 
from  the  fact  that  it  becomes  enlarged  following  castration; 
as  it  also  does  during  pregnancy  when  the  ovaries  temporarily 
change  their  function.  It  is  suggestive  also  that  at  that  time 
the  hands  sometimes  enlarge  and  the  face  changes. 

Perhaps  no  structure,  in  proportion  to  its  size,  is  more  inter- 
esting or  of  less  importance  than  our  pineal  gland.  Of  the 
size  of  a  grain  of  wheat,  it  lies  high  up  in  the  base  of  the 
brain  behind  and  above  the  pituitary.  It  reaches  full  de- 
velopment at  the  seventh  year,  then  begins  to  atrophy,  and 
in  adults  has  become  connective  tissue  and  "brain  sand": 
minute  grains  of  phosphate  and  carbonate  of  lime.  This 
"sand"  is  often  found  elsewhere  in  the  brain,  even  in  fetal 

Descartes  held  that  the  pineal  is  the  seat  of  the  soul.  He 
was  long  on  philosophy,  but  short  on  comparative  anatomy. 
Yet  possibly  he  was  nearer  the  truth  than  he  realized. 
Millions  of  years  ago  the  pineal  was  a  third  eye  and  looked 
straight  up  to  heaven.  Extinct  reptiles  have  a  hole  in  the 
skull  for  this  pineal  eye.  The  sphenodon,  an  almost  extinct 
New  Zealand  reptile,  is  the  only  living  animal  with  a  pineal 
organ  that  resembles  a  true  eye.  Most  lizards  have  a  pineal 
organ,  and,  above,  a  hole  in  the  roof  of  the  skull.  The  hole 
is  covered  by  a  scale;  the  organ,  therefore,  cannot  function  as 
a  true  eye,  it  may  serve  as  an  organ  for  sensing  lights  and 
shadows.  Except  the  lowest  fishes,  all  vertebrates  have  a 
relic  of  this  "eye."  In  Man  the  "relic"  has  a  vestige  of  the 
optic  nerve. 

No  pineal  hormone  has  yet  been  discovered,  nor  is  it  yet 
certain  that  it  is  a  gland.  Nothing  certain  is  known  of  its 
function,  nor  is  it  certain  that  it  has  any  importance  beyond 



pre-adolescence,  if  it  has  any  then.  From  the  fact  that  tumors 
of  the  pineal  are  often  associated  with  precocious  mental  and 
sexual  development,  it  is  inferred  that  its  business  is  to  pro- 
mote early  physical  growth  and  retard  sexual  development. 
But  this  is  only  inference — the  tumor  may  also  have  involved 
the  mid-brain. 


To  Lavoisier's  dictum:  "Life  is  a  chemical  function,"  we 
might  add,  "and  ceases  to  function  without  sugar."  At  any 
rate,  we  eat  more  sugar  than  we  should,  because  our  body 
fmds  sugar  where  we  little  suspect  it.  Sugar  is  the  finest 
fuel  our  blood  can  find  to  keep  life  on  the  move.  When  any- 
thing happens  to  our  sugar  refinery,  sugar  storage,  or  sugar 
delivery,  we  suffer  from  one  of  several  more  or  less  fatal 

The  regulator  of  sugar  metabolism  is  a  group  of  secreting 
organs  known  as  the  islands  of  Langerhans,  in  the  "sweet- 
breads" or  pancreas,  and  which  act  as  a  gland  of  internal 
secretion.  Its  hormone,  insulin,  is  delivered  direct  to  the 
blood.  Pancreatic  juice,  an  important  digestive  fluid,  is 
delivered  by  the  duct  of  Wirsung  to  the  alimentary  canal. 

Diabetes  (from  the  Greek  "to  go  through")  follows  when 
the  islands  of  Langerhans  stop  functioning.  The  isolation  of 
insulin,  chiefly  due  to  Banting  and  McLeod,  ends  a  search  of 
many  long  years  and  closes  one  of  the  most  interesting  chap- 
ters in  the  new  science  of  endocrines.  There  is  a  remedy  for 
diabetes  mellitus,  but  no  cure.  Life  can  be  prolonged  "in- 
definitely" ;  but  insulin  feeding  alone  will  not  prevail  without 
control  of  diet. 

It  is  significant  that  of  the  more  than  a  million  sufferers 
from  diabetes  in  this  country  90  per  cent  are  overweight; 
and  that  of  those  over  fifty  years  of  age  there  are  twenty  fat 
for  every  thin  diabetic  sufferer.  From  which  we  infer  that 
the  human  pancreas  as  regulator  of  sugar  metabolism  tends 



to  break  down  when  we  take  on  more  fat  than  we  require.  We 
take  on  fat  when  we  eat  more  sugars  and  fats  than  we  use  up. 

The  pancreas  is  a  very  vital  organ.  Its  removal,  or  the 
removal  of  seven-eighths  of  it,  is  followed  by  a  condition 
like  that  of  diabetes:  increased  urine,  abnormal  thirst  and 
hunger,  death.  Its  hormone,  delivered  to  the  blood,  regulates 
the  output  of  glycogen  from  the  liver,  and  is  necessary  for 
the  building  of  glycogen  and  the  oxidation  of  sugar  by  the 
body  tissues.   This  is  the  route: 

The  portal  blood  carries  glucose  to  the  liver.  The  liver 
converts  glucose  into  glycogen  (animal  starch).  The  liver 
itself  is  not  an  endocrine  gland,  although  it  does  deliver 
sugar  to  the  blood  direct.  It  stores  up  no  hormones,  but  it 
reeks  with  extracts.  It  stores  vitamins;  it  destroys  fat;  it 
stores  glycogen.  It  is  a  vital  organ.  Nothing  takes  its  place 
or  can  do  its  refining.  All  its  processes  depend  upon  its  own 
liver  cells.  How  it  converts  sugar  into  animal  starch  for 
storage  purposes  and  how  it  reconverts  it  into  sugar  when 
the  secretion  from  the  islands  of  Langerhans  tells  it  to  do 
so,  are  not  known.  It  does.  If  the  islands  stop  sending 
messages,  the  liver  gives  up  all  its  sugar  to  the  blood,  but  the 
body  cells  cannot  store  or  burn  it  and  so  it  is  filtered  by  the 
kidneys  from  the  blood  and  passed  on  to  the  bladder. 

The  spleen  has  no  duct;  it  has  no  secretions.  It  is  not  a 
gland.  Just  what  it  is  no  one  knows.  Its  functions  are  not 
specific,  nor  does  its  removal  seem  to  impair  health,  growth, 
or  longevity.  In  the  fetus  it  is  probably  an  incubator  for 
red  blood-cells;  after  birth  it  seems  to  be  an  incinerator  of 
red  blood-cells.  They  work  so  hard  carrying  oxygen  they 
wear  themselves  out  in  from  ten  to  fifteen  days.  Perhaps  10 
per  cent  of  all  red  blood-cells  are  destroyed  each  day.  It  is 
possible  that  an  "enlarged"  spleen  destroys  red  cells  faster 
than  it  should;  it  may  therefore  be  responsible  for  chronic 
anemia.  It  does  produce  a  chemical  catalyzer;  its  enzymes 
convert  nucleins  into  uric  acid. 

The  secretions  of  the  stomach  and  small  intestine — gastrin 



and  secretin — are  drugs  to  be  used  on  the  spot.  They  are 
dangerous  drugs  if  used  elsewhere  in  or  on  the  body.  Stomach 
and  intestine  may  produce  hormones.  May.  If  they  do,  they 
presumably  regulate  the  pancreas,  gastric  glands,  etc. 

Neither  lymph  nor  lymph  "gland"  has  any  endocrine  func- 
tion. Nor  has  the  blood.  A  quart  of  my  blood  may  tide  you 
over  until  you  can  make  enough  to  supply  your  loss.  But 
my  blood  is  my  blood;  it  is  in  dynamic  equilibrium,  con- 
stantly changing  to  meet  the  specific  requirements  of  the 
particular  families  of  cells  on  its  route  in  my  body. 

Kidneys,  if  veal  or  sheep,  are  good  to  eat.  They  are  good 
as  food.  But  "extract  of  kidney"  is  as  good  to  repair  a  faulty 
kidney,  or  to  treat  uremia  or  nephritis,  as  powdered  glass  is 
to  restore  a  watch  crystal.  The  kidney  is  not  a  gland,  it 
secretes  nothing.   It  is  a  filter  or  excretory  organ. 

Other  "extracts"  are  doped  out  to  meet  the  demand.  Brains 
for  dementia  praecox,  tetanus,  epilepsy,  etc.  Such  treatment, 
says  Carlson,  is  "less  rational  than  the  principles  and  prac- 
tices of  Mrs.  Eddy.  Perhaps  we  could  make  for  greater 
progress  if  the  manufacturers  [of  dried  brains]  could  be 
induced  to  use  the  brains  of  horses  instead  of  asses  and  sheep 
for  their  raw  material,  and  the  finished  product  was  taken  by 
the  doctor  instead  of  being  given  to  the  patient." 

Dried  lungs,  tonsils,  retina,  iris,  nasal  mucous  membrane, 
and  such  can  be  had  in  the  drug  stores;  "cures"  for  tuber- 
culosis, tonsilitis,  etc.  Rubbish.  The  few  hormones  that  are 
really  known  are  so  powerful,  so  useful,  so  wonderful,  that 
they  have  encouraged  imitators.  The  result  is  a  new  crowd 
of  quacks,  ready  to  "feed"  anybody  anything  that  sounds  like 
something  and  is  therefore  presumably  a  remedy. 


Gonads  is  Greek  for  seeds.  As  the  organs  or  glands  of 
reproduction  of  both  sexes  produce  seeds,  it  is  a  convenient 
and  polite  word  for  testes  and  ovaries.   But  the  newspapers  in 



referring  to  gonad  operations,  rejuvenescence,  etc.,  always 
speak  of  "glands."  Only  the  context  makes  it  certain  that 
the  "glands"  referred  to  are  not  the  parotid  or  thyroid  or 
some  other  equally  "respectable"  gland. 

This  reluctance — which  Robinson  characterizes  as  "shame- 
faced, prudish,  and  squeamish" — to  face  the  facts  necessary 
to  solve  some  of  the  simple  but  vital  problems  of  everyday 
life  is  almost  a  chronic  psychosis,  with  signs  now  and  then  of 
a  tendency  to  sanity. 

Psychology  has  diagnosed  the  "impurity  complex"  and 
shown  us  what  is  back  of  the  blatant  prude  who  advertises 
his  or  her  "purity."  It  has  also  shown  that  the  purity  of  the 
ignorant,  when  purchased  at  the  price  of  a  stifled  natural 
curiosity,  is  not  a  safe  and  sane  "purity."  The  study  of 
biology  has  begun  to  break  down  this  impurity  complex  and 
the  unholy,  unnatural  doctrine  begun  by  early  Christian 
monks  that  the  sex  impulse  is  man's  sign  of  degradation  and 
the  source  of  his  most  devilish  energy.   Nature  knows  better. 

Sex  is  a  primary  biologic  function  of  all  life  above  the 
lowest.  Its  characters  and  qualities  have  an  ancient  lineage. 
Its  impulse  is  as  real  as  is  the  force  which  makes  the  tides  to 
ebb  and  flow.  It  has  profoundly  influenced  structure  and 
behavior.  It  is  a  fundamental  element  of  all  higher  life;  its 
external  characters  a  neat  advertising  dodge  of  Nature  by 
which  she  sells  her  wares  and  thereby  insures  her  family. 

To  sex  we  owe  more  than  poetry;  we  owe  the  song  of  birds, 
all  vocal  music  and  the  voice  itself,  the  plumage  that  comes 
to  supreme  glory  in  the  bird  of  paradise,  the  mane  of  the 
lion,  the  tresses  of  women,  the  blush  of  the  maiden,  the  beard 
of  men,  and  all  higher  forms  of  life  in  plant  and  animal 
world.  It  is  woven  into  every  fabric  of  human  life  and  lays 
its  finger  on  every  custom.  To  the  debit  side  of  the  sex  ac- 
count we  must  charge  many  silly  stupidities  and  some  of  die 
foulest  injustices  which  go  to  make  the  thing  we  call  human 
culture  the  amazing  and  variegated  mosaic  that  it  is. 

We  are  more  enlightened  than  we  were,  but  we  have  not 



yet  reached  the  stage  where  the  mere  mention  of  sex  will  not 
provoke  some  one  to  respond  with  a  reproach  or  an  insult. 
Whole  blocks  on  Main  Street  assume  that  "sex  knowledge" 
is  of  questionable  propriety,  or,  at  best,  to  be  kept  dark  in 
"doctor-books";  or  regard  it  as  the  banal  possession  of  the 
frankly  shameless.  As  a  result,  most  pseudo-scientific  "sex" 
literature  slops  over  into  the  emotions  and  lets  facts  alone,  or 
presents  facts  under  disguises.  Much  of  it  has  no  biologic 
background  or  anything  of  the  laws  of  life  which  govern 
man  no  less  than  every  living  thing.  It  is  fear  (sometimes 
called  "reverence")  that  makes  us  "let  sex  alone."  It  is 
mock  modesty  and  foolish  shame,  masquerading  under  the 
name  "decency,"  that  compels  museums  to  clothe  marble 
Fauns  and  plaster  Joves  and  bronze  Cupids  with  plaster-of- 
Paris  fig  leaves,  often  awry  or  nicked  at  the  corner. 

Back  of  much  of  this  confusion  and  nonsense  is  the  para- 
dox which  culminated  in  Puritanism:  Marriage  is  a  divine 
institution  and  the  god  of  Love  is  a  saint,  but  sex  is  shameful 
and  Cupid  is  a  carnal  beast. 

Man  is  "high,"  "animals"  are  "low" — without  minds  and 
of  course  can  have  no  "souls."  We  have.  Ours  is  a 
"divine"  parentage,  our  bodies  "sacred."  Hence  art,  from 
Phidian  sculpture  to  sophomoric  poem,  tends  to  the  greater 
glory  of  Man:  men  and  women  more  like  gods  and  god- 
desses; gods  and  goddesses  glorified  men  and  women. 

And  so  it  came  about  that  the  commonest  thing  in  nature 
next  to  keeping  alive  became  invested  with  the  sanctity  of 
heaven.  Love  begins  with  a  capital  "L"  because  it  is  sacred. 
So  it  is.  Without  it  the  world  of  man  stops.  There  would 
be  no  more  fishes  in  the  sea  if  the  males  did  not  like  the 
females.  Love  is  fine.  Put  it  on  a  pedestal,  magnify  it, 
glorify  it,  deify  it.  But  why  leave  Cupid  on  the  pedestal? 
To  worship  him  blindly  is  on  a  par  with  any  other  fetishism, 
and  quite  as  intelligent.  Take  him  down  and  dust  him  off, 
repair  his  broken  ears,  mend  his  battered  nose,  refeather  his 



arrows  and  restring  his  bow.  Why  not  have  a  look  at  him? 
What  is  he  made  of? 


Certain  glands  are  essential  to  life.  Their  removal  is  fol- 
lowed by  death.  Not  so  the  gonads  proper.  They  may  be 
removed,  in  fact  are  constantly  being  removed — especially 
those  of  women — in  the  operating  rooms.  What  happens? 
The  patient  lives.  The  gonads  are  not  necessary  for  indi- 
vidual life,  only  for  that  of  the  race  or  species. 

Physical  differences  between  men  and  women  are  sexual. 
There  are  primary  and  secondary  differences.  The  second- 
ary characters  begin  to  assume  definite  form  in  both  sexes 
at  the  beginning  of  puberty.  These  characters  are  by- 
products of  the  male  and  female  gonads. 

The  gonads  are  like  true  duct  glands  in  that  they  discharge 
their  secretion  through  ducts,  but  this  secretion,  unlike  that 
of  other  duct  glands,  is  not  discharged  into  and  consumed 
by  the  parent  body.  The  gonads  have  an  additional  func- 
tion: they  secrete  a  hormone  which  regulates  the  appearance 
and  growth  of  the  secondary  characters  and  supplies  the 
impulse  back  of  sex  behavior.  In  this  they  are  like  true 
endocrines,  which  deliver  their  regulating  secretions  direct 
to  the  blood  stream.  Thus  the  gonads  are  also  glands  of 
internal  secretion. 

For  ages  it  has  been  known  that  boys  or  girls  deprived  of 
their  gonads  before  puberty  develop  into  "womanly"  men  or 
"manly"  women  and  throughout  life  retain  an  infantile  type 
of  body.  Eunuchs  ("guardians  of  the  couch,"  created  for 
religious  and  social  ends),  develop  neither  the  voice  nor  the 
beard  of  men;  in  women  similarly  altered  the  mammary 
glands  remain  undeveloped,  their  bodies  do  not  become  so 

Experiments  on  chickens  show  that  when  the  ovaries  are 
completely  removed  from  a  young  hen,  she  begins  to  take 



on  the  secondary  sexual  characters  of  the  male :  she  develops 
comb,  wattles,  and  spurs;  her  plumage  becomes  more  bril- 
liant; she  grows  larger;  she  takes  on  the  typical  behavior  of 
the  rooster.  This  can  only  mean  that  the  ovary  itself,  by  its 
own  internal  secretion  taken  up  into  the  blood  stream,  has 
power  to  modify  the  body  in  the  direction  of  the  female  sex. 
It  has  been  inferred  that  secondary  male  characters  were 
potentially  present  in  the  hen,  but  were  inhibited  by  the 

Moore  implanted  a  piece  of  ovary  in  a  young  male  guinea- 
pig.  His  body  was  modified ;  his  teats  came  to  resemble  those 
of  a  pregnant  female.  His  behavior  showed  no  sign  of 
acquired  feminine  instincts.  Another  investigator  reports 
"timid,  shy,  and  mothering-the-young"  behavior  of  a  guinea- 
pig  thus  altered.  But  all  investigators  agree  that  the  male 
gonad  transplanted  into  an  altered  young  female  leads  to 
change  in  both  body  and  behavior.  She  becomes  aggressive, 
quarrelsome,  and  behaves  like  a  typical  male  toward  other 
males  and  toward  females  in  general.  Her  physical  modifi- 
cation is  equally  profound. 

Cattle  breeders  have  long  known  that  the  female  of 
bisexual  twins  is  generally  sterile  and  tends  toward  the  male 
in  physical  characters.  Such  sterile  females  are  called  free- 
martins,  Lillie  investigated.  The  twins,  it  seems,  develop 
independently  in  the  two  horns  of  the  cow's  uterus,  but  join 
below  in  the  outer  fetal  envelope.  Through  this  they 
exchange  blood.  The  precocious  hormone  of  the  fetal  male 
sterilizes  the  fetal  female  ovary!  It  seems  so  extraordinary 
as  to  be  almost  incredible. 

But  there  is  no  doubt  about  sterile  freemartins,  nor  about 
the  fact  of  their  intercommunicating  arterial  blood  stream 
in  fetal  development.  Lillie's  conclusions  mean  that  the 
male  fetus  secretes  a  specific  gonad  hormone  before  its 
gonads  are  really  formed;  this  male  hormone  sterilizes  the 
female  gonad. 

The  fact  that  both  pancreas  and  thyroid  hormones  are 



known  to  be  secreted  in  intrauterine  life  lends  weight  to  the 
inference  that  the  sex  hormones  themselves  are  produced  by 
the  primitive  germ  cells.  That  there  is  no  exchange  of 
gonad  hormones  between  the  human  fetus  and  its  mother 
seems  evident  from  the  fact  that  the  developing  male  fetus 
does  not  influence  the  sex  life  of  the  mother. 

In  other  words,  while  the  nature  of  the  sex  impulse  is  the 
same  in  the  two  sexes,  the  sex  hormones  themselves  are  not 
the  same.  But  they  are  not  antagonistic.  "Maleness"  can 
be  produced  in  females;  "femaleness"  in  males.  The  male 
hormone  in  a  young  spayed  female  modifies  both  her 
behavior  and  her  body.  The  female  hormone  in  a  castrated 
young  male  body  modifies  only  the  body. 

The  male  fetus  does  not  modify  its  mother:  she  is  still  in 
possession  of  her  own  gonads.  The  male  fetus  modifies  the 
behavior  and  sterilizes  the  gonads  of  its  twin  female  fetus. 
Human  twins,  if  "identical,"  are  always  of  the  same  sex; 
if  not  identical  there  is  no  exchange  of  blood,  for  each  has 
its  own  fetal  membranes. 


The  adult  female  gonads  in  mammals  contain  ova  in 
varying  stages  of  ripening  and  interstitial  stroma  or  cells. 
Bodi  seem  to  have  an  identical  origin  and  both  pass  through 
similar  changes  in  development. 

The  ova  or  germ-cells  develop  in  Graafian  follicles.  When 
ripe  they  burst  through  the  wall  of  the  ovary.  The  ovum 
escapes.  The  ruptured  follicle  reassembles  and  enlarges  for 
about  a  week,  filling  the  rent  in  the  ovarian  wall.  Then  it 
breaks  up  and  is  absorbed  before  the  next  follicle  matures. 
But  if  the  ovum  is  fertilized,  the  follicle  continues  to  develop 
for  three  months  and  then  persists  until  the  end  of  pregnancy. 
The  ruptured  and  changing  follicle  is  called  the  corpus 
luteum  (yellow  body)  because  of  its  color  after  the  escape 
of  the  ovum.    Corpora  lutea  are  supposed  to  produce  a 



hormone.  The  ovary  does  produce  hormones,  how  or  where 
is  not  well  understood;  nor,  in  fact,  has  the  ovary  itseK  parted 
with  half  of  its  mysteries. 

Removal  of  the  ovary  or  its  absence  or  atrophy  in  the 
young  is  followed  by  an  arrest  of  secondary  sexual  char- 
acters. The  primary  sexual  characters,  including  the  breasts, 
remain  in  an  infantile  condition.  The  lunar  cycle  does  not 
appear.  The  body  tends  toward  fat.  Removal  in  the  adult 
leads  to  atrophy  of  the  primary  sexual  characters,  the  sup- 
pression of  all  sex  functions,  and  of  most  sex  behavior. 

The  ovary  can  be  transplanted  from  one  part  of  the  body 
to  another;  it  long  continues  to  function  as  an  endocrine 
gland,  no  femininity  is  lost,  nor  does  the  lunar  cycle  cease. 
When  transplanted  from  one  body  to  another  it  may  form 
blood  connections,  but  it  eventually  degenerates.  But  as  long 
as  a  piece  of  it  remains  alive  in  its  new  hostess  her  sex  life, 
including  lunar  cycle,  continues  "normal." 

For  transplantation  purposes  a  bit  is  as  good  as  the  entire 
ovary.  Where,  then,  does  its  hormone  come  from?  It  pro- 
duces one:  Carlson  thinks  probably  several.  None  has  yet 
been  isolated  or  can  be  detected  in  the  human  blood.  But 
Allen  and  Doisy  claim  to  have  isolated  a  mammalian  ovary 
hormone  which  resembles  the  long-desired  "love  potion"  of 
romance  and  literature.  "Female  animals  treated  with  it 
take  the  initiative  in  courtship,  even  at  an  early  age." 
Injected  into  young  animals,  they  "become  mature  before 
they  normally  would." 

This  hormone  is  an  "extract  of  the  contents"  of  the 
Graafian  follicles.  Why  not?  It  is  all  plausible.  Nothing 
seems  more  certain  than  that  the  sex  impulse  and  all  second- 
ary sexual  characters  in  all  mammalian  females  are  depend- 
ent upon  the  normal  functioning  of  the  ovaries.  The 
physiological  and  anatomical  changes  in  the  Graafian 
follicles  during  the  life  cycle  are  both  profound  and  sig- 
nificant.   As  they  are  the  source  of  the  ova,  it  is  reasonable 



to  suppose  that  they  carry  the  control  of  sex  impulse  or 
behavior  and  the  acquired  secondary  characters. 

When  the  follicle  erupts  and  discharges  the  ovum,  it 
becomes  the  corpus  luteum.  W^en  the  corpus  luteum  is 
destroyed,  pregnancy  ends  and  ovulation  is  resumed.  Hence 
the  inference  that  the  corpus  luteum  is  responsible  for  uterine 
changes  leading  to  the  implantation  of  the  embryo  and  for 
the  early  growth  of  the  fetus.  Wlien  corpora  lutea  are  fed 
to  hens,  they  lay  no  eggs;  hence  the  inference  that  during 
pregnancy  they  inhibit  the  ripening  of  the  Graafian  follicle 
and  so  prevent  ovulation  and  menstruation  and  restrain  the 
sex  impulse.  They  influence  the  mammary  glands,  but  the 
development  of  these  during  pregnancy  is  believed  to  be  due 
to  hormones  from  the  fetus  to  the  maternal  blood.  The 
mammae  themselves  are  not  known  to  have  any  endocrine 
function.  Their  removal  does  not  prevent  child-bearing  or 
have  any  other  effect  than  "psychic  and  cosmetic,"  according 
to  Carlson.  But  removal  of  the  ovary  is  removal  of  feminine 

No  mammals  below  Primates  have  anything  approaching 
the  specific  lunar  cycle  of  a  woman's  life  between  puberty 
and  the  menopause.  While  slight  menstrual  hemorrhage 
occurs  in  many  species  of  Primates,  it  is  essentially  a  human 
process  regulated  by  the  normal  and  mature  ovum,  but  its 
function  is  not  yet  understood  nor  is  there  agreement  as  to 
just  what  takes  place  or  why  there  is  such  wide  range  of 
individual  variation.  The  climacteric  is  reached  when  no 
more  Graafian  follicles  mature. 

Disordered  sex  life — except  the  menopause — in  woman 
may  be  due  to  other  than  ovarian  deficiencies:  other  endo- 
crines  may  be  involved,  perhaps  the  adrenals  or  the  pituitary. 
It  is  not  certain  that  ovarian  extracts  are  anything  but 
extracts  and  so  of  possible  value  only  through  suggestion. 
Nor  can  luteal  extracts  check  human  ovulation;  the  corpus 
luteum  can.  Nor  is  it  at  all  certain  that  any  ovarian  extracts 
on  the  market  contain  any  hormone.    It  is  certain  that  the 



normal  ovary,  through  its  hormones,  functions  for  all  second- 
ary female  characters  and  has  the  specific  sex  functions  for 
such  distant  organs  as  uterus,  placenta,  and  mammae. 

The  functions  of  personal  incubation  assumed  by  one-half 
of  the  race  ages  ago  necessitated  an  elaborate  internal 
mechanism.  For  its  perfect  functioning,  elaborate  and  com- 
plicated controls  were  necessary.  It  follows,  and  is 
biologically  inevitable,  that  the  sex  life  of  the  female  of  the 
human  species  is  far  more  complex  than  is  that  of  the  male. 
But  it  is  biologically  conceivable  that  in  a  no  great  distant 
future  reproduction  in  the  human  species  can  be  radically 
altered.  Under  such  controlled  breeding,  the  ovaries  of  only 
physically  sound  individuals  would  be  used  and  to  the  limit 
of  their  two  hundred  ova;  these  would  be  fertilized  artificially 
and  developed  in  man-made  incubators.  Such  control  of 
human  life  seems  quite  attainable;  much  more  so  than  the 
synthesis  of  life  in  any  form. 


The  male  gonads  contain  spermatogonia.  These  develop 
into  germ-cells  and  fertilize  the  ovum.  This  involves  two 
factors:  the  ovum  is  stimulated  to  develop;  the  male  inherit- 
ance is  afforded  a  vehicle.  The  gonad  performs  this 
function  through  external  secretions.  But  as  the  spermato- 
gonia themselves  are  cells  early  set  aside  in  embryonic 
development  and  are  not  products  of  chemical  change  as  are 
the  secretions  of  other  duct  glands,  the  gonads  in  their  repro- 
ductive functions  are  not  comparable  to  other  glands.  They, 
as  the  ovaries,  are  arsenals  where  ammunition  for  life  is 

Between  the  cell  clusters  where  spermatogonia  develop  are 
other  groups  of  cells,  the  interstitial  cells  of  Ley  dig.  These 
cells  appear  in  the  embryo  before  the  spermatogonia  cells. 
Under  the  X-rays  they  are  not  affected;  the  sperm-cells  are. 
When  the  gonad  does  not  descend,  or  in  one  transplanted  into 



another  body,  the  germ-cells  atrophy;  the  Leydig  cells  are 
unaffected  or  may  increase  in  size.  Thus  they  show  greater 
power  of  resistance  than  the  germ-cells;  they  are  embry- 
ologically  older. 

Absence,  atrophy,  or  extirpation  of  the  gonads  in  the 
young  male  prevents  the  appearance  of  the  secondary  sexual 
characters — beard,  change  in  the  larynx  and  character  of 
skeleton — and  checks  development  of  the  reproductive 
mechanism.  It  also  delays  the  final  ossification  of  the  heads 
of  the  long  bones  and  the  sutures  of  the  skull.  It  lowers  the 
rate  of  metabolism,  increases  the  tendency  to  take  on  fat,  and 
lowers  vasomotor  irritability.  It  perhaps  leads  to  changes  in 
the  endocrine  system,  enlarging  the  adrenal  cortex  and  the 
pituitary,  diminishing  thyroid  growth,  checking  thymus 
involution.  It  changes  behavior:  less  bold,  less  pugnacious, 
more  infantile;  it  shuts  off  the  sex  impulse.  In  the  adult, 
loss  of  gonads  stops  the  sex  impulse  and  tends  to  atrophy 
of  the  reproductive  mechanism,  to  obesity  and  lowered 

Nothing  else.  Life  is  not  shortened,  nor  mental  or 
physical  efficiency  impaired.  Hence,  as  Carlson  points  out, 
"growing  old"  is  not  to  be  charged  to  gonad  dysfunction,  but 
to  damage  by  age  to  all  the  tissues  of  the  body.  Gonad 
removal  leads  only  to  loss  of  structure  and  function  specific 
for  sex  life. 

Curiously,  evidence  seems  to  indicate  that  gonadectomy 
in  the  two  sexes  leads  to  opposite  changes  in  the  adrenals: 
in  males,  to  an  increase  of  15  per  cent;  in  females,  to  a 
decrease  of  20  per  cent.  The  net  result  is  to  increase  the 
resemblance  between  the  two  sexes. 

The  spermatogonia  cells  are  simply  future  germs.  This 
throws  the  responsibility  for  the  regulation  of  the  develop- 
ment of  sex  mechanism  and  function  on  the  interstitial  cells. 
Moore  has  recently  furnished  new  proof  of  this.  In 
cry ptor chic  individuals  (the  gonads  remain  within  the 
abdominal  cavity)  there  may  or  there  may  not  be  spermato- 



gonia;  if  not,  the  individual  is,  of  course,  sterile,  but  if  the 
Leydig  cells  are  present,  the  individual  is  male  in  structure, 
function,  and  behavior. 

When  the  vas  deferens  or  excretory  duct  of  the  gonad  is 
ligatured,  the  spermatogonia  are  said,  but  not  proved,  to 
atrophy;  the  germ-cells  cannot,  of  course,  be  discharged  and 
consequently  the  individual  is  sterile.  But  as  long  as  the 
Leydig  cells  are  intact,  sex  life  is  unimpaired.  This  is  the 
basis  of  the  famous  operation  of  Steinach,  and  is  based  on 
two  assumptions:  that  ligation  of  the  vas  deferens  increases 
Leydig  cell  growth;  that  it  causes  the  spermatogonia  appa- 
ratus to  atrophy.  Neither  of  these  assumptions  is  yet  proved; 
in  fact,  Oslund  asserts  that  both  assumptions  are  contrary 
to  fact,  that  vasectomy  produces  no  testicular  changes  and 
"cannot  be  looked  upon  as  a  method  of  causing  rejuve- 

When  gonads  are  transplanted  into  other  male  bodies,  the 
individual  maintains  sex  life  as  long  as  enough  Leydig  cells 
remain  alive.  This  was  Steinach's  first  method  of  "rejuvena- 
tion": "a  biological  futility,  a  catering  by  the  surgeon  to  the 
elements  of  sex  degeneracy,"  says  Carlson.  And  adds :  if  the 
transplant  be  from  goat  or  monkey,  "the  surgeon  is  the 
monkey,  the  patient  is  the  goat." 

Grafts  of  goats  or  monkeys  are  not  yet  known  to  become 
vascularized,  nor  is  it  known  that  the  Leydig  cells  survive 
up  to  two  years.  It  is  known  that  the  sperm-cells  do  not 
survive  transplanting.  It  is  not  settled  how  long  a  gonad  will 
live  after  removal:  "most  glands  die  in  a  few  hours."  At 
most,  the  graft  can  only  temporarily  restore  the  sex  impulse; 
any  true  "rejuvenescence"  of  mind  or  body  can  only  come 
from  suggestion. 

Suggestion  likewise,  thinks  Carlson,  is  all  that  backs  the 
whole  tribe  of  "genital"  extracts  on  the  market  and  which 
are  guaranteed  "cures"  for  everything  from  growing  pains 
to  melancholia,  including  goiter,  scurvy,  cholera,  anemia, 
delirium  tremens,  and  syphilis. 



The  adrenal  cortex  and  Leydig  cells  have  a  common 
embryonic  origin,  but  they  come  to  have  quite  different 
functions.  No  gland  can  play  the  role  of  the  Leydig  cells; 
if  they  are  lost,  sex  life  is  lost.  The  only  compensation 
possible  is  in  the  direction  of  general  metabolism. 

In  both  sexes,  gonad  hormones  are  specific  regulators  of 
sex  characters  up  to  puberty;  the  hormones  that  sustain  sex 
life  during  maturity  are  possibly  quite  different  from  those 
which  determined  development.  They  are  the  catalyzers  of 
development;  they  must  vary  with  the  stage  or  degree  of 


The  race  of  bisexual  animals  depends  on  the  coming 
together  of  male  and  female.  Moths  find  their  mates  by 
their  olfactory  antennae;  fishes,  by  color  and  behavior;  frogs, 
by  voice  and  touch;  birds,  by  voice  and  sight;  mammals,  by 
scent.  Man  is  a  mammal,  but  he  has  traded  his  scent  organ 
for  a  nose  and  he  kills  his  odor  with  soaps  or  artificial 
scents.  He  discovers  his  mate,  as  do  birds,  by  voice  and 
sight.  Either  sex,  deprived  of  the  gonads,  has  no  need  for 
secondary  characters;  nor  do  they  appear  unless  the  gonads 
function  as  endocrine  or  "puberty"  glands.  That  is  the  busi- 
ness of  the  hormones  of  the  gonads :  so  to  catalyze  developing 
structure  that  the  two  sexes  already  determined  in  prenatal 
development  will  not  look  or  sound  alike,  but  will  look  and 
sound  good  to  each  other.  Secondary  sex  characters,  there- 
fore, are  additional  devices  of  nature  for  making  each  sex 
easily  recognized  by  and  more  attractive  to  the  opposite  sex. 
Hence  the  "instinctive"  repugnance  of  normal  men  for 
"manly"  women;  of  normal  women  for  "womanly"  men. 

Puberty  means  sexual  maturity;  the  individual  is  ready 
to  assume  the  next  stage  in  normal  development:  parentage. 
Modern  life  departs  from  the  normal;  it  pays  no  attention  to 
the  facts  of  puberty.    The  age  of  marriage  tends  to  become 



more  and  more  remote  from  sex  maturity;  the  education  of 
the  youth  proceeds  as  though  tliere  were  no  such  tiling  as 

In  normal  life  in  girls,  as  in  the  females  of  all  mammals, 
the  milk  glands  at  puberty  take  on  rapid  growth.  The  most 
noticeable  changes  in  the  boy  are  the  appearance  of  hair 
on  the  face  and  a  startling  change  in  the  growth  of  the 
cartilages  and  vocal  cords  of  the  larynx.  The  voice  at  first 
breaks;  by  die  time  it  becomes  normal  again  it  has,  as  a  rule, 
dropped  one  full  octave.  Mean^vhile  the  boy  outgrows  his 
collars  faster  than  he  does  his  hats.  In  bodi  sexes  hair 
appears  on  the  pubes. 

^Tiile  early  growth  depends  on  the  amount  and  nature  of 
the  food  and  on  general  hygienic  conditions,  puberty  as  a 
rule  appears  earliest  in  individuals  of  short  stature.  Thus, 
it  comes  earlier  among  Italians  than  Scandinavians,  the 
difference  agreeing  widi  die  relative  statures  of  the  two 

Girls  of  European  descent  grovr  faster  than  boys  between 
the  ages  of  ten  and  fifteen.  Between  eleven  and  fourteen  the 
girls  are  actually  taller;  between  t^v^elve  and  fifteen,  heavier. 
At  fifteen  the  rate  of  the  girTs  begins  to  diminish. 
The  skeleton  begins  to  mature,  for  both  sexes,  at  puberty-. 
The  girl's  pelvic  girdle  undergoes  a  marked  change  in  width. 
She  also  becomes  more  plump. 

Between  the  fourteenth  and  eighteenth  years  for  girls,  and 
bet^veen  die  fifteenth  and  t^ventieth  years  for  boys,  a  new 
im.pulse  enters  life.  This  impulse,  only  vaguely  present 
before,  is  now  the  impelling  force.  For  this  reason:  puberty 
means  more  than  mere  physical  change,  it  means  sex 
maturity;  it  is  a  result  as  well  as  an  event.  Besides  the 
physical  changes  which  increase  the  demands  for  food- 
energy*,  the  whole  organism  is  involved  in  maturity. 

The  boy  or  girl  is  now  preoccupied  with  a  new  order  of 
internal  affairs.  This  necessarily  involves  the  entire  nervous 
mechanism — not  in  its  structure,  but  in  the  nature  of  the 



situations  to  which  it  must  now  adjust  the  individual.  The 
second  great  crisis  in  life  is  at  hand.  It  is  a  different  indi- 
vidual, the  world  itself  is  different.  Up  till  now  the 
primordial  instinct  of  self-preservation  has  had  only  one 
main  drive:  food-hunger;  to  this  is  now  added  the  drive  of 
mate-hunger.  It  enters  the  race  fresh  and  will  have  its  say. 
The  body  itself,  under  both  direct  and  indirect  influence  of 
the  sex  mechanism,  is  stirred  to  its  depths.  The  inhibitory 
centers  in  the  spinal  cord  are  lowered;  the  susceptibility  of 
the  brain  is  increased  through  the  vasomotor  nerves. 

The  outcome  of  the  conflict  is  determined  by  many 
factors.  In  animal  life  and  the  majority  of  the  human  race, 
the  result  is  courtship  and  mating.  We  generally  solve  the 
problem  satisfactorily,  but  promiscuity  and  certain  unbi- 
ologic  and  unsocial  habits,  with  sex  complexes  leading  to 
neuroses,  seem  to  be  increasing. 

But  the  real  point  in  all  this  is  that  the  gonads  normally 
do  function  as  endocrine  glands.  As  a  consequence  the 
two  sexes  do  differ,  in  bodily  structure,  in  behavior,  in 
organic  necessity.  As  Ellis  puts  it:  "A  man  is  a  man  to 
his  very  thumbs,  and  a  woman  is  a  woman  down  to  her  little 
toes."  Specialization  in  bodies  is  older  than  civilization, 
and  there  has  always  been  a  real  difference  between  men 
and  women  beyond  that  of  the  primary  sex  organs.  Which 
prompts  Keith  to  remark:  "No  legislation  can  blot  out| 
structural  differences  that  have  taken  geological  epochs  to  I 
produce."  But  substitution  of  gonads  can.  In  fact.  Riddle 
cites  two  cases  of  female  birds  that  laid  eggs  and  were  in  all 
respects  true  females;  they  ceased  to  be  females,  became 
males  in  form  and  function,  and  fathered  young.  No  sur- 
gical operation  involved:  only  destruction  of  female  organs 
due  to  tuberculosis;  male  organs  replaced  them,  followed  by 
male  behavior.  What  all  this  signifies  is  not  yet  known. 
But  this  much,  at  least:  sexual  characters  depend  on  sex 
hormones;  complete  sex-transformation  in  adults  is  possible. 




Shorn  of  her  locks  and  dressed  in  man's  costume,  woman 
is  still  woman.  Yet  how  many  times  she  has  passed  for  a 
man — as  a  sailor,  a  soldier,  a  coal-miner!  Her  femininity 
tends  to  disappear  beneath  the  male's  make-up.  The  two 
sexes  differ  in  degree  rather  than  in  kind. 

The  assumption  that  women  are  not  as  "adult"  as  men 
has  no  basis  in  fact.  Yet  we  keep  hearing  about  the 
"infantile"  character  of  woman!  Her  body  does  more  nearly 
resemble  the  infant's  than  does  the  male's,  but  this  only 
states  half  the  truth.  In  all  that  is  essentially  "human,"  her 
body  is  more  human  than  man's.  The  adult  male  may  be 
less  infantile  than  the  adult  female ;  he  is  also  less  essentially 

The  typical  female  skull  is  so  delicate  and  smooth  that 
sex  can  be  postulated  nineteen  times  out  of  twenty.  It  has 
none  of  the  asperities,  ridges,  and  prominences  which  mark 
the  skull  of  the  male.  The  bones  of  her  face,  especially  of 
the  jaws,  are  much  more  "human"  than  are  the  corresponding 
bones  in  man's  jaws. 

The  weight  of  the  skull  compared  with  the  weight  of  the 
long  bones  shows  this  interesting  progression:  greatest  pro- 
portionate weight  of  skull,  children  first,  women  next;  then 
short  men,  tall  men,  apes.  In  weight  of  skull  compared  with 
that  of  thigh  bones,  the  advantage  again  is  with  woman. 

Our  pelvic  girdle  is  in  some  respects  more  "human"  than 
the  skull  itself.  It  is  the  distinguishing  sex  trait  in  the  skele- 
ton. To  the  trained  observer  there  is  no  mistaking  the  pelvic 
girdle  of  a  female  for  that  of  a  male.  A  moment's  reflection 
will  show  why  this  should  be  so.  In  man,  the  pelvis  supports 
the  abdominal  viscera  and  continues  the  support  of  the 
upright  body  from  the  legs.  To  perform  these  two  functions 
it  became  modified  in  two  directions:  broader,  by  expansion 
of  the  iliac  crests;  more  compact  and  substantial,  by  a 
greater,  broader  sacrum.    The  sacrum  is  the  key  of  the 



pelvic  arch;  it  carries  the  backbone,  and  incidentally  the 
entire  upper  part  of  the  body.  Woman's  pelvis  has  traveled 
further  than  man's  in  this  regard.  Her  breadth  across  iliac 
crests  is  proportionately  greater  than  the  depth  from  pubic 
symphysis  to  top  of  sacrum.  Her  sacrum  also  is  more  dis- 
tinctively human  in  its  great  breadth. 

The  two  bones  which  form  the  basin  of  the  pelvis — of 
which  the  iliac  crests  are  easily  felt  beneath  the  skin  at  the 
sides  of  our  abdomen — meet  in  front  to  form  the  pubic 
symphysis.  The  joint  of  the  symphysis  is  made  by  a  strong 
ligament  which  yields  under  pressure.  In  the  male  pelvis  the 
ligament  is  narrow;  in  the  female,  wide.  The  slope  of  the 
pubic  bones  below  the  joint  is  also  greater  in  the  female,  an 
additional  factor  in  enlarging  the  outlet  of  her  pelvis. 

Can  our  pelvic  girdle  become  more  "human"?  The  upper 
rim  might  become  better  adjusted  to  support  the  body,  but 
a  girdle  so  narrowed  as  to  prevent  childbirth  stops  variation 
in  that  direction.  This  seems  to  set  a  limit  to  the  size  of  the 
human  brain  at  birth.  In  most  still-born  deliveries  the  head 
is  too  large  to  pass  the  bony  outlet  of  the  pelvis.  We  may 
assume  that  the  limit  of  brain  size  at  birth  has  been  reached. 

Man's  pelvis  is  long,  narrow,  strong;  woman's,  broad, 
shallow,  delicate,  roomy.  Her  thighs  are  relatively  greater. 
Her  carriage  differs  from  man's  because  the  heads  of  her 
thigh  bones  are  farther  apart.  As  she  transfers  her  body 
from  one  thigh  to  the  other  in  walking,  she  must  make  a 
greater  effort.  Her  pelvis  is  a  compromise  between  an  arch 
to  support  viscera  and  an  outlet  to  make  childbirth  possible. 

Women  among  so-called  savages  are  notoriously  as  strong 
as  men,  although  there  is  always  a  division  of  labor  between 
the  sexes.  The  most  splendid  human  bodies  I  have  ever 
seen  were  those  of  black  women  working  under  extremely 
primitive  conditions  in  gold  and  emerald  mines  in  South 
America.  Their  backs,  shoulders,  and  arms  spoke  of  great 
strength,  but  there  were  no  bulging  muscles.    Even  apart 



from  their  breasts,  their  bodies  were  unmistakably 

The  luxuriant  head  hair  of  women  of  European  descent  is 
not  a  mark  of  sex:  it  is  the  barber  that  makes — or  made — 
the  difference.  Chinese  and  Indians  were  proud  of  their  hair 
and  had  as  much  of  it  as  their  spouses.  Head  hair  is  a  race 
and  culture  and  not  a  sex  factor. 

Sex  differences  are  strongly  marked  in  brain  size  among 
man  and  apes.  The  male  gorilla's  brain  is  18  per  cent 
larger  than  the  female's;  the  orang's,  14  per  cent;  the  chim- 
panzee's, 8  per  cent;  man's,  12  per  cent.  But  the  disparity 
is  due  to  general  disproportion  in  size  between  the  two  sexes. 
Structurally  the  brains  of  the  two  sexes  are  the  same,  and  as 
compared  to  weight  of  body  are  heavier  in  women  than  in 
men.  If  a  relatively  large  brain  is  a  "human"  trait,  the 
brain  of  the  child  stands  highest,  woman  next. 

More  males  are  born  than  females;  in  the  so-called  white 
races,  about  105  males  for  every  100  females.  Yet  woman's 
longevity  counter-balances  the  disproportion;  at  the  age  of 
fifty,  unless  migrations  or  wars  upset  the  calculation,  we  may 
expect  to  find  as  many  women  as  men. 

Differences  between  the  tv/o  sexes,  yes.  The  male  spe- 
cializes in  the  direction  of  brute  strength  and  the  courage 
that  goes  with  it;  the  female  retains  her  youthfulness  in  body 
in  general  and  especially  in  face  and  neck.  With  age  some 
women  begin  to  appear  neutral,  halfway  between  man  and 
woman.  But  the  vicious  element  in  such  phrases  as 
"Woman's  proper  work"  and  "Woman's  true  sphere"  is  the 
assumption  implied  of  lack  of  capacity.  To  assume  that  her 
capacity  for  intelligent  behavior  or  human  adjustments  is 
less  than  man's  is  biologically  and  physiologically  absurd. 

Comte's  idea  is  better  biology  and  sound  psychology: 
"Between  two  beings  so  complex  and  so  diverse  as  man  and 
woman,  the  whole  of  life  is  not  too  long  for  them  to  know 
one  another  well  and  to  learn  to  love  one  another  worthily." 




The  endocrines  are  new  to  science ;  some  have  only  recently 
been  discovered;  the  function  of  some  only  recently  sus- 
pected; not  one  is  yet  perfectly  understood.  Yet  their 
astounding  importance,  and  the  claims  quacks  make  that 
gland  "extracts"  are  cure-alls  and  gonad  operations  a  Foun- 
tain of  Youth,  conspire  to  whet  the  appetite  for  facts  faster 
than  the  laboratories  can  sift  them  out.  Hence  new  crops 
of  quacks  who  dispense  pills  or  elixirs  or  their  services  with 
a  knife  or  a  ligature;  and  a  raft  of  literature  which,  as 
Hoskins  says,  "for  its  vagaries,  fantastic  exuberance,  and 
wholesale  marvel-mongering,  is  without  a  peer  in  the  history 
of  modern  science." 

Little  is  yet  known  of  endocrine  co-operation,  or  what  takes 
place  in  some  when  others  fail.  No  gland  or  other  organ 
functions  for  or  by  itself,  or  lives  a  life  of  independence; 
the  entire  body  mechanism  makes  up  the  organism.  The 
business  of  the  glands  is  the  business  of  the  body  as  a  going 
concern,  to  keep  it  fit  and  enable  it  to  function,  as  infant, 
as  youth,  as  adult,  as  senility  overtakes  it. 

Carlson  thinks  the  following  endocrine  teamwork  proba- 
ble: the  gonads  cannot  function  if  the  thyroid  and  possibly 
the  pituitary  and  adrenal  cortex  are  subnormal;  removal  of 
thyroid  and  probably  of  gonads  stimulates  the  pituitary; 
thyroid  extract  seems  to  stimulate  the  adrenals  and  the 
pituitary,  as  it  does  the  heart,  liver,  and  kidneys;  removal 
of  the  thyroid  stimulates  the  parathyroids — at  least  in  tad- 
poles; tumor  of  the  adrenals  induces  gonad  precocity; 
removal  of  the  gonads  retards  atrophy  of  the  thymus  and 
leads  to  change  in  pituitary  and  adrenal  cortex. 

It  seems  certain  that  removal  of  the  thyroid  is  followed  by 
cretinism  in  children,  myxedema  in  adults;  of  the  para- 
thyroids, by  death;  of  the  pancreas,  by  death;  of  the  adrenals, 
by  death;  of  the  pituitary,  by  infantilism  in  children,  by 
impotence  in  adults;  of  the  thymus,  by  sexual  precocity;  of 



the  gonads,  by  sex  infantilism  in  children,  by  atrophy  of 
secondary  sex  characters  in  adults;  of  the  pineal,  by  no 
known  endocrine  effect. 

Most  of  each  endocrine  may  be  removed  from  an  animal 
without  apparent  loss  of  function  of  its  internal  secretion; 
the  inference  is  that  no  endocrine  normally  works  to  its  full 
capacity.  A  normal  thyroid  stores  up  enough  to  last  several 
weeks ;  the  adrenin  reserve  only  suffices  for  a  few  hours.  But 
in  general  almost  nothing  is  known  of  the  storage  capacity 
or  rate  of  production  of  hormones.  It  is  known  that  symp- 
toms may  not  appear  after  removal  of  the  thyroid  for  weeks 
or  months.  Removal  of  the  pancreas  is  followed  by 
symptoms  within  ten  hours ;  of  the  parathyroids  and  adrenal 
cortex,  almost  at  once. 

Post-mortems  prove  these  connections:  thyroid  with 
cretinism  and  myxedema;  adrenals  with  Addison's  disease 
and  death;  pituitary  with  infantilism;  pancreas  with  diabetes. 

Known  positive  results  from  large  endocrines  or  excessive 
endocrine  secretions  are  few;  it  is  not  yet  proved  that  large 
glands  yield  large  results.  It  is  only  inference  that  excessive 
thyroid  secretion  causes  toxic  goiter;  of  the  anterior  lobe  of 
the  pituitary,  gigantism;  of  the  adrenal  medulla  and  the 
thyroids,  excess  pep;  of  the  adrenal  cortex,  the  pineal  and 
pituitary,  sex  precocity;  of  the  gonads,  excessive  sex  urge; 
of  the  thyroid,  diabetes.  Results  claimed  for  excessive 
thymus  and  pineal  activity  are  not  yet  proved.  As  their  loss 
produces  no  known  effect,  what  could  necessarily  result  from 
their  increased  function? 

Can  endocrine  disorders  be  "cured"  through  the  nerves 
of  endocrine  secretion?  The  pineal,  the  posterior  lobe  of  the 
pituitary,  and  the  medulla  of  the  adrenals  are  themselves 
modified  nerve  cells.  But,  except  the  medulla,  neither  the 
cutting  of  all  the  nerves  to  all  the  endocrines  nor  artificial 
stimulation  shows  any  effect  on  the  body  or  change  in  the 
glands  themselves.  The  nerves  to  the  endocrines  seemingly 
have  little  or  nothing  to  do  with  their  secretions.    But  most 



quacks  feed  their  patients  "gland  extracts."  Few  hormones 
are  yet  known.  Apart  from  insulin,  adrenalin,  pituitrin,  and 
thyroxin,  the  quacks  themselves  know  nothing  further  of  any 
of  the  various  extracts  they  often  feed  for  unknown  diseases. 
With  "diet  and  rest,"  extracts  are  as  potent  as  the  bread  pills 
of  old. 

The  endocrines  are  part  of  the  body,  and  so  subject  to 
heredity,  tumors,  lesions,  tuberculosis  and  other  infections, 
especially  to  faulty  metabolism.  The  influence  of  the  thyroid 
and  pancreas  on  general  metabolism  and  growth  is  funda- 
mental. They  must,  therefore,  influence  all  the  body,  includ- 
ing all  the  glands.  The  thyroid  normally  functions  only  if 
there  is  enough  iodine  in  the  food.  If  in  doubt,  take  cod- 
liver  oil  or  eat  sea  grass. 


The  endocrine  glands  are  intrinsic  parts  of  the  body,  in 
intimate  touch  with  living  processes.  Muscular  activity 
starts  the  sweat  glands,  the  muscles  are  fed  with  sugar,  the 
adrenals  pour  their  secretion  into  the  blood  to  neutralize  the 
toxins  of  fatigue,  and  so  on. 

Arrest  of  development  or  over-stimulation  of  the  endo- 
crines brings  about  change  which  may  be  harmful  or  of 
benefit  to  the  body.  Giants,  fat  women,  cretins,  men  and 
women  under-sexed  and  over-sexed,  imply  variation  in  tlie 
structure  and  functioning  of  these  glands.  Apparently  some 
individuals  are  better  fitted  for  the  work  of  life  than  others; 
still  others  are  so  well  fitted  that  they  overdo  it.  No  two 
human  beings  are  exactly  alike;  they  do  not  and  cannot  act 
alike.  We  should  hesitate  before  passing  harsh  moral  judg- 
ments upon  activities  due  to  inherited  or  acquired  physical 

Possibly  several  generations  must  pass  before  the  real  and 
definite  function  of  the  endocrines  is  fully  understood.  Possi- 
bly new  drugs  will  replace  the  old;  pills  compounded  on 



formulae  learned  in  nature's  laboratory,  elixirs  for  all  the 
ills  of  body  and  mind  we  are  now  heir  to.  The  fact  that 
the  emotions  are  expressions  of  states  under  control  of  the 
glands  and  closely  bound  up  with  the  sympathetic  nervous 
system  opens  up  an  enormous  field  for  speculative  possi- 
bilities. Russell  thinks  it  will  be  possible  to  make  people 
hot-headed  or  timid,  strongly  or  weakly  sexed,  and  so  on, 
as  may  be  desired.  In  case  of  war  the  timid  souls  will  simply 
be  injected  with  certain  glandular  extracts  or  synthesized 
regulators ! 

There  is  another  angle.  Almost  nothing  has  yet  been  done 
on  the  racial  anatomy  of  the  endocrines.  Are  shape  and 
size  of  head,  face,  nose,  eyes,  teeth,  lips,  length  of  limbs, 
and  stature,  character  and  shape  of  hair,  due  to  the  activity 
of  the  endocrines?  Keith  thinks  this  possible  and  suggests 
that  whites  are  what  they  are  because  they  have  more  thyroid, 
adrenal,  pituitary,  and  gonad  hormones  than  other  races,  and 
that  inherited  condition  of  glands  points  a  mechanism  through 
which  heredity  controls  development  and  established  type 
variations.  Racial  character — such  as  emotional  reactions, 
intellectual  capacity,  and  personality  in  general — would  thus 
vary  likewise,  and  for  the  same  reason. 

This  compounding  of  elixirs  for  all  ills  from  endocrines, 
and  the  solution  of  the  problem  of  race  and  individual  varia- 
bility by  reference  to  variation  in  glandular  mechanism  and 
functioning,  take  us  too  far  from  reality,  too  far  into  possi- 
bilities. We  of  to-day  are  going  concerns  and  our  interest 
in  the  past  is  only  in  the  light  it  can  shed  on  what  we  are 
and  can  do  to-day.  And  that  is  a  personal  question — for 
this  reason: 

No  two  human  beings  are  alike.  Every  human  being  con- 
tinues throughout  life  to  change.  The  question.  What  is 
good  for  the  human  machine  as  a  going  concern?  is,  there- 
fore, always  personal  and  individual;  it  all  depends.  Some 
want  to  go  fast,  others  prefer  to  go  slow.  One  may  see  ideal 
life  only  in  the  chest  of  Hercules;  another,  in  the  wings  on 



the  feet  of  Mercury.  But  most  humans  are  born  right;  there 
is  nothing  the  matter  with  our  inheritance. 

There  is  a  normal  rate  of  growth  and  of  growing  old. 
Too  much  or  too  little  upsets  the  normal  rate.  With  nothing 
to  chew  on,  normal  development  of  jaws,  teeth,  muscles  and 
glands  of  mastication  need  not  be  expected.  Without  work 
or  play,  normal  development  of  the  bones  and  muscles  of 
the  motor  mechanism  is  not  to  be  expected.  "Exercises"  and 
"physical  culture"  are  too  often  taken  as  pills  and  drugs: 
controls,  but  not  cures. 

Glued  to  a  chair  with  head  tied  to  an  account  book  or  a 
last  makes  for  less  than  the  normal  work  designed  by  nature 
for  heart  and  lungs.  By  and  by  lungs  and  heart  lose  their 
original  capacity  for  work,  as  do  muscles  which  are  never 

Man  has  inherited  a  body  of  a  certain  type  which  functions 
best  under  certain  conditions  of  food,  work,  rest,  sleep,  etc. 
These  conditions  also  are  part  of  each  individual's  inherit- 
ance and  consequently  must  vary  with  individuals.  Sauce 
for  the  goose  is  not  necessarily  sauce  for  the  gander.  It  is 
true  that  some  Jack  Sprats  can  eat  no  fat,  their  wives  can 
eat  no  lean. 

The  real  question,  then,  for  adults,  is  personal.  Is  my 
machine  capable  of  giving  the  service  I  shall  require  to 
carry  me  where  I  want  to  go?  Many  are  ready  enough  to 
answer.  No.  But  they  are  not  willing  to  distinguish  between 
hunger  and  appetite  or  count  calories  instead  of  cost;  and 
they  will  walk  a  mile  for  a  cigarette,  but  not  a  foot  for 
health's  sake. 

But  every  child  is  entitled,  in  civilization  as  in  savagery, 
to  the  full  development  of  its  normal  inheritance.  Civiliza- 
tion has  taken  curious,  often  monstrous,  bents;  and  even 
now  in  many  places  does  not  hesitate  to  deny  children  the 
free  exercise  of  their  human  birthright  to  develop  sound 
minds  in  sound  bodies. 




"How  can  a  man  be  born  when  he  is  old?"  asked  Nico- 
demus.  And  answered  his  question  with  another,  "Can  he 
enter  a  second  time  into  his  mother's  womb  and  be  born?" 

Life  does  grow  old  and  young  again,  but  nature  knows  of 
no  such  rebirth  as  puzzled  the  brain  of  Nicodemus  and  has 
become  entangled  in  the  folk-customs  of  so  many  peoples. 
Growing  old  and  growing  young  again  are  age  changes,  both, 
in  Child's  words,  "merely  one  aspect  of  Werden  und 
Vergehen,  the  Becoming  and  Passing-away  which  make  up 
the  history  of  the  universe." 

What  is  it  that  grows  old  and  young  again?  "Life"  grows 
old.  What  is  "life"?  We  have  certain  criteria — none  too 
good — for  living  beings;  and  certain  criteria  for  death.  But 
life  itself,  can  it  be  defined  or  described?  Is  it  a  thing  or 
an  action,  a  process  or  a  function?  There  are  living  beings 
and  processes  or  functions  of  living.  But  life  cannot  be 
restricted  by  this  or  that  process  or  function,  nor  described 
as  this  or  that  chemical  compound;  nor  as  any  one  certain 
or  particular  form.  Life  is  something  more  than  process  or 
function,  compound  or  form. 

Life  is  a  result  of  action  in  something.  The  "something" 
is  a  physical  body  of  protoplasm.  The  "action"  is  change, 
many  and  complex  and  dynamic.  Dynamic  changes  and 
physical  body  are  inseparable;  they  influence  and  condition 
each  other. 

Man  himself  is  such  a  physico-chemical  system  of  dynamic 
changes.  What  disturbs  this  system  disturbs  the  being;  the 
being  is  the  system.  If  the  disturbance  is  so  great  that  the 
being  cannot  readjust  itself,  the  system  breaks  down,  the 
being  dies. 

Probably  we  shall  never  know  just  how  life  itself  began. 
If  we  could  concoct  a  reaction-complex  capable  of  living, 
we  might  not  know  just  when  life  begins.    The  complex 



structure  and  the  dynamic  process  known  in  living  beings 
are  always  bound  by  a  bond  which,  broken,  ends  life. 

Hence  life  is  unlike  any  machine  made  by  man.  In 
machines,  dynamic  processes  take  place  in  complex  struc- 
tures, but  we  can  always  distinguish  between  process  and 
structure.  Nor  can  the  machine  function  until  the  structure 
is  completed.  But  the  living  being  always  functions  and 
has  been  functioning  since  life  began.  The  structure  deter- 
mined function,  function  determined  structure.  In  other 
words,  life  constructs  its  own  machine  by  living. 

Living  means  changing.  Living  processes  depend  on 
change.  The  body  during  growth  adds  to  itself  certain  chem- 
ical compounds  which  are  physiologically  stable;  that  is, 
they  are  of  such  a  nature  that  they  can  be  built  into  the  body. 
The  energy  used  up  during  the  building  or  growth  period 
is  furnished  by  the  oxidation  of  less  stable  compounds. 

The  growing  child  is  a  rapidly  changing  being.  We  age 
fastest  during  childhood.  The  rate  of  metabolism  is  then 
highest.  In  old  age  it  slows  down.  In  starvation,  new  com- 
pounds are  not  synthesized  as  fast  as  old  compounds  are 
broken  down.  But  starvation  only  ends  in  death  after  many 
weeks  because  the  most  vital  functions  are  carried  on  in  the 
most  active  organs.  Because  of  their  activity  they  are  fed, 
first  by  stored  fuel  or  fats,  next  by  muscle.  When  this  fuel 
is  exhausted,  death  soon  follows. 

Thus,  growing  and  growing-old  are  simply  two  aspects  of 
the  same  complex  dynamic  activity.  Both  are  phases  of 
production  and  progress.  We  shall  know  how  to  grow  young 
when  we  know  how  to  increase  the  rate  of  metabolism  or 
vital  change,  and  how  to  change  the  cells  of  the  body  so  that 
an  increase  in  rate  of  metabolism  is  possible. 

The  nature  of  the  rejuvenescence  that  hinges  on  the  internal 
secretions  of  the  sex  glands  is  not  part  of  the  problem  raised 
by  Nicodemus.  A  man  "renewing  his  youth"  is  one  thing; 
Life  growing  young  again  is  quite  a  different  thing. 

Life  resides  only  in  living  beings;  the  way  they  are  born 



again  when  old  is  one  phase  of  evolution.  The  process  is 
called  reproduction,  of  which  there  are  many  methods.  Have 
they  all  something  in  common?  Or  is  there  some  unique 
quality  in  reproduction  in  man  and  higher  animals  not  found 
in  the  lowest  animals?  Whether  there  is  or  not,  the  fate  of 
the  individual  organisms  concerned  is  different.  Those  that 
reproduce  by  division  do  not  die;  at  any  rate,  as  Weismann 
said,  there  is  no  "corpse."  Death  does  overtake  those  that 
reproduce  bisexually.  But  reproduction  in  man  is  bisexual. 
Man,  as  individual,  dies;  he  cannot  be  born  again  when  he 
is  old,  or  young.  The  life  that  is  in  him  can  grow  young 
again;  but  only  by  a  process  known  as  reproduction.  That 
is  the  nature  of  reproduction. 

Rebirth,  then,  as  that  word  is  commonly  understood,  is 
biologically  inconceivable.  It  is  possible  that  to-day  complex 
chemical  substances  are  in  process  of  becoming  of  the  nature 
of  protoplasm  in  which  living  reactions  take  place,  and  which, 
could  we  observe  them,  would  be  recognized  as  living  beings. 
But  the  laws  of  chance  are  against  it  and  all  our  conceptions 
of  evolution  are  against  it.  A  possible  "rebirth"  is  quite  as 

All  that  is  known  of  the  facts  of  evolution  and  all  theories 
as  to  the  mechanism  of  evolution  favor  the  idea  that  every 
man  and  every  being  alive  to-day  have  been  alive  since  life 
was  evolved.  It  is  even  more  certain  that  every  man  and 
every  organism  alive  to-day  began  life  as  part  of  an  adult  or 
"old"  organism.  But  as  man  and  all  organisms  begin  their 
individual  existence  as  young  organisms,  it  follows  that 
something,  somewhere,  somehow,  has  renewed  its  youth,  has 
become  young  again. 

Call  this  "something"  life.  Life  itself  has  grown  old 
during  evolution.  The  life  that  is  in  man  and  in  all  living 
beings  is  old,  millions  of  years  old;  it  grows  young  through 

There  are  only  two  great  kinds  of  reproduction:  without 
sex  or  agamic  (no  wife),  and  with  sex  or  gametic  (wife). 



In  agamic  reproduction,  a  new  individual  arises  from  part 
or  parts  of  the  body  which  have  come  to  lie  beyond  tlie 
physiologic  limit  of  size;  they  are  physiologically  isolated 
parts  of  the  body.  In  gametic  reproduction,  as  in  man,  the 
germs  of  life  are  also  isolated — so  far  as  the  parent  indi- 
vidual is  concerned,  "dead  and  shed,"  Child  says.  But  by 
adult  life  they  are  also  already  highly  specialized  and  have 
already  completed  their  growth. 

Weismann  assumed  that  the  germ-cells  are  young  and  that 
they  are  special  only  in  the  sense  that  they  are  set  aside  at 
once  in  embryonic  development  for  the  purpose  of  reproduc- 
tion; hence  the  doctrine  of  the  "continuity  of  the  germ- 
plasm."  He  also  assumed  that  nothing  could  influence  these 
cells;  hence  there  could  be  no  transmission  of  a  character 
acquired  by  the  body  of  the  individual  carrying  these  cells. 

But  germ-cells  in  bisexual  reproduction  are  in  no  sense 
"young";  they  are  no  more  "special"  than  any  other  group 
of  cells  of  the  body.  Only  after  the  embryo  has  begun  to 
build  its  body  are  the  cells  resulting  from  cell  divisions  set 
aside  to  become  the  store  of  future  germ-cells. 

Ovum  and  sperm  are  old  cells,  especially  the  sperm.  They 
are  as  differentiated  as  almost  any  cells  of  the  body.  They 
have  ceased  to  grow;  they  have  a  low  rate  of  metabolism; 
but  the  dynamic  substratum  present  in  both  is  old  protoplasm, 
grown  old  during  the  long  years  of  evolution.  As  a  result 
it  has  become  stable,  highly  individualized.  Otherwise  there 
could  have  been  no  evolution  of  such  structural  permanence 
and  complexity  as  we  find  in  man  and  higher  animals. 

Hence  evolution  is  not  chiefly  change  in  form,  but  change 
in  the  dynamic  reaction  system  of  protoplasm.  As  indi- 
vidual man  develops  and  grows  old,  so  evolution  itself  repre- 
sents a  change  from  a  less  stable  to  a  more  stable  condition 
in  the  dynamic  reaction  system. 

The  protoplasm  of  the  germ  has  also  evolved.  As  a  result 
of  that  evolution,  it  has  reached  such  a  stage  of  diff'erentiation 
that  it  can  no  longer  react  alone,  as  it  does  in  lower  organ- 



isms.  Only  by  marriage  of  ovum  and  sperm  is  the  carrier 
of  life  brought  back  to  pre-embryonic  conditions.  Fertiliza- 
tion is  the  only  rejuvenescence  known  to  man  and  higher 

By  fertilization  the  old  protoplasm  of  the  ovum  is  recon- 
stituted, reduced,  rejuvenated.  The  fertilized  ovum  is 
younger  than  ovum  and  sperm  were  before  they  united  in 
fertilization.  It  begins  life  anew;  and  as  a  parasite.  Having 
escaped  from  the  old  individual,  it  is  no  longer  subject  to 
the  inhibitions  of  the  old.  Not  until  it  begins  its  post-natal 
existence  will  it  be  subject  to  the  inhibitions  of  human  society. 

The  fertilized  human  ovum  is  possibly  less  an  "individual" 
than  a  protozoon,  but  that  ovum  is  protoplasm  which  has 
been  evolved  to  the  point  that  within  it  is  potentially  present 
the  foundation  of  the  structure  and  form  of  an  adult  man  or 
woman.  That  ovum  can  do  what  the  growing  child  does:  so 
transform  food  materials  that  it  can  build  some  into  new 
protoplasm  and  incorporate  the  new  within  its  body;  it  can 
oxidize  other  food  materials  to  set  free  the  energy  it  uses  in 
building  its  body.  This  transformation  of  food  materials  is 
metabolism,  change,  the  foundation  of  the  function  of  life. 

Life  itself,  then,  is  change  in  protoplasm,  itself  a  dynamic 
entity.  Change  or  reaction  is  determined  by  its  physico- 
chemical  constitution  and  by  its  relation  to  the  external  world. 
Adaptations  are  thus  seen  as  simply  special  features  of  this 
relation.  The  mechanism  by  which  life  renews  its  youth  is 
such  an  adaptation. 

I  agree  with  Child  that  it  is  impossible  to  conceive  of  evolu- 
tion and  of  so-called  "adaptations"  without  assuming  that 
"acquired  characters"  can  be  inherited.  But  often,  as  Child 
points  out,  tens  of  thousands  of  generations  may  have  been 
necessary  for  such  inheritance  to  become  appreciable. 

Without  such  adaptation  there  would  be  no  such  living 
beings  as  man  and  higher  animals.  There  might  be  some- 
thing else  "just  as  good,"  for,  as  Russell  says,  we  have  only 
our  own  word  for  it  that  man  is  superior  to  the  ameba;  we 



can  have  no  idea  what  the  ameba  would  think  of  the 

Nor  need  it  necessarily  disturb  our  self-esteem  to  realize 
that  only  our  own  conditioned  human  eyes  see  man  as  a 
"finished  product"  of  evolution.  Pearl  aptly  argues  that 
Omnipotence  could  have  made  a  much  better  machine  than 
the  human  body — "that  is,  if  he  had  first  learned  the  trick 
of  making  a  self -regulating  and  self -reproducing  machine. 
Each  part  of  the  human  body  is  only  just  good  enough  to 
get  by — workmanship  like  that  of  an  average  man.  If  evolu- 
tion happens  to  be  furnished  with  fine  materials  it  has  no 
objection  to  using  them,  but  is  equally  ready  to  use  shoddy 
if  it  will  hold  together  long  enough  to  get  the  machine  by 
the  reproductive  period."  Which  is  another  way  of  saying 
that  evolution's  main  concern  is  the  continuation  of  life  rather 
than  of  this  or  that  kind  of  living  beings. 

But  this  does  not  necessarily  mean  that  senility  and  death 
are  the  inevitable  ends  of  human  existence,  either  as  indi- 
viduals or  as  race. 


Man  and  other  warm-blooded  animals  are  killed  by 
freezing  or  by  boiling,  or  by  cutting  off  their  air  or  food 
supply.  Death  comes  also  in  other  ways:  foreign  substances 
are  taken  in,  or  get  into  the  body,  which  cannot  be  eliminated 
or  combated;  or  vital  parts  of  the  body  are  injured  by 
mechanical  or  other  means.  In  other  words,  we  die  when 
the  conditions  necessary  for  life  have  been  so  changed  that 
life  becomes  impossible. 

We  are  specific  mechanisms  in  which  certain  physico- 
chemical  changes  occur  in  a  certain  routine  order.  We  live 
as  long  as  the  mechanism  is  in  good  repair  and  the  changes 
take  place.  Mechanism  and  changes  are  one.  They  only 
seem  two  when  life  is  looked  at  from  diff'erent  angles. 
Together,  they  represent  life:  they  balance;  they  are  in 



equilibrium;  they  are  adjusted;  they  harmonize.  Normally 
they  go  through  life  together,  always  preserving  this  har- 
mony. Cut  off  a  leg:  the  blood  does  not  stop  circulating; 
it  readjusts  itself  to  the  changed  condition.  If  it  cannot 
readjust,  what  is  left  of  the  machine  stops. 

Anything  which  necessitates  serious  readjustment  is 
pathologic.  The  body  is  diseased  when  under  conditions  to 
which  it  is  not  adjusted.  There  are  almost  as  many  diseases 
as  there  are  cells  in  the  body;  certainly  many  more  than  there 
are  tissues  or  organs.  Disease  in  any  cell,  cell-group,  tissue, 
organ,  or  system,  is  felt  everywhere.  The  noise  of  a  tooth- 
ache may  be  faint  by  the  time  it  reaches  the  toe,  but  the  toe 
is  none  the  less  interested.  A  gallstone  may  be  of  particular 
concern  only  to  the  liver,  but  the  liver's  concern  is  the  body's 

Life  is  played  to  a  certain  tune;  it  need  not  be  a  monkey- 
wrench  to  set  its  chords  jangling.  An  undigested  bean  will 
do,  or  a  bean  in  the  windpipe;  or  any  one  of  a  thousand 
things.  But  despite  the  nicety  of  the  balances  and  co-ordina- 
tions which  make  for  normal  health,  the  body's  capacity  for 
readjustment  is  remarkable.  It  is  not  we  who  fight  for  life, 
but  our  living  bodies.  They  hang  on  to  life  in  spite  of  much 
we  do  to  discourage  them. 

This  fighting  power  is  part  of  our  inheritance.  We  cannot 
grow  a  new  limb,  much  less  a  new  head  or  a  new  trunk,  as 
some  animals  can.  We  can  store  fuel  fat  as  no  lower  animal 
can;  and  experience,  as  no  other  animal  can.  It  is  not  to 
be  charged  to  our  inheritance  if  we  fill  our  experience-loft 
with  rubbish.  We  can  make  repairs;  in  some  tissues,  very 
extensive  repairs.    We  can  make  antibodies. 

These  antibodies  illustrate  the  vast  numbers  and  the 
enormous  complexity  of  the  processes  that  go  on  under  our 
skin,  and  the  fine  adjustments  that  must  always  be  going  on 
to  keep  the  body  tuned  up  for  the  business  of  life. 

Something  seems  to  happen  when  the  body  faces  civiliza- 
tion.   There  is  probably  not  a  single  adult  in  this  country 



with  a  body  in  perfect  tune:  what  the  life-insurance  com- 
panies would  call  "Glass  AA  risk." 

Of  1,000  employees  examined  by  one  motor  company, 
just  1,000  were  imperfect.  Of  a  group  of  hundreds  of 
thousands  examined,  10  per  cent  had  "slight  defects,"  the 
other  90  per  cent  had  "defects  not  so  slight."  Nearly  40 
per  cent  of  the  white  school  children  of  Washington  have 
defects — ^teeth,  vision,  hearing,  etc. — ^which  can  be  located 
without  removing  their  clothes.  Over  45  per  cent  of  Penn- 
sylvania's youth  were  not  physically  fit  to  be  sent  overseas 
to  be  shot  at. 

This  means  two  things. 

More  get  past  Cultural  Selection  than  Natural  Selection; 
the  openings  in  the  sieve  are  larger,  the  nature  of  the  struggle 
is  different.  Runts  which  grow  to  Roosevelts  and  Steinmetzes 
in  civilization  die  early  in  nature.  Runts  which  become 
nothing  but  charges  on  society  also  survive  in  Cultural 
Selection.  In  other  words,  individuals  with  inherited  or  post- 
natal defects  live  because  society  supplies  that  which  their 
bodies  lack  to  maintain  a  balance  on  life.  A  freak  in  nature 
does  not  live  long;  in  civilization,  it  makes  good  money. 

Millions  of  minor  defects  are  due  to  bad  food-digestion. 
We  inherit  omnivorous  teeth  and  thirty  feet  of  alimentary 
canal  made  for  every  kind  of  food  but  cooked  and  pre- 
digested.  Also,  powerful  muscles  hung  to  strong  bones, 
leveraged  for  work.  The  body  was  built  on  the  theory  that 
these  muscles  would  be  worked.  The  very  work  the  muscles 
are  supposed  to  do  is  part  of  the  process  of  living.  The 
flow  of  lymph  and  the  circulation  of  the  blood  in  general 
depend  on  a  mechanism  built  to  function  best  when  the  motor 
apparatus  is  in  motion.  That  is  why  we  have  bones  and 
muscles,  and  that  is  why  we  have  blood  and  lymph. 

One  bad  tooth  in  an  ancient  skull  or  among  savages  is  an 
anomaly.  A  perfect  set  in  an  adult  American  is  a  far  greater 
anomaly.  Toothache  means  that  the  cavity  is  almost  in  to 
the  nerve.    That  means  almost  in  to  the  entire  body.  Our 



body  is  a  double  sack,  each  sealed  up  tight.  Whatever  breaks 
through  the  wall  of  either  sack  (skin  or  alimentary  canal) 
is  a  foreign  body  and  potential  death. 

Apart  from  congenital  influence,  most  defects  originate  in 
the  mouth  or  alimentary  canal.  Children  are  not  born  with 
defective  gums,  bad  tooth  germs,  narrow  palate,  stunted  jaws, 
adenoid  growths,  or  diseased  tonsils.  Our  inheritance  is 
usually  all  right;  we  do  not  use  it  according  to  directions. 
The  newborn  comes  with  a  full  set  of  tools  for  building  a 
full-grown,  sound,  healthy,  defectless  body;  too  often  it  is 
treated  as  a  cunning  little  toy  to  a  doting  household  for  six 
years  or  so,  and  is  thereafter  chiefly  of  interest  to  the 
statistician  collecting  Defects  or  Defectives. 

Metabolism  is  adjustment  for  the  functions  of  life.  We 
inherit  an  adjustment  machinery  adapted  for  a  certain  kind 
of  active  life,  but  before  it  is  of  age  we  have  taught  it  a 
"civilization"  that  was  never  contemplated  by  the  designer 
of  the  machine.  Civilization  is  kept  busy  keeping  the 
machine  in  repair. 

One  good  defect  deserves  another.  Defects  lead  to  other 
defects.  Many  bodies  are  kept  so  busy  repairing  leaks  in 
the  lungs,  or  picking  cinders  out  of  the  fuel,  or  keeping 
foreigners  out  of  the  blood,  that  they  have  no  time  for  the 
main  business  of  life:  giving  their  owner  a  lifelong  joy-ride. 


Weismann  held  that  death  is  an  "advantageous  adapta- 
tion." For  what?  To  whom?  Looks  like  nonsense.  Osier 
said  that  man  is  as  old  as  his  arteries.  There  was  enough 
truth  in  this  to  make  it  take.  It  means  even  less  to  say  that 
man  is  as  old  as  his  endocrine  glands.  Arteries  and  glands 
are  as  old  as  the  man. 

Metchnikofl'  held  that  because  of  "disharmonies"  in  the 
body,  the  phagocytes  devoted  too  much  time  to  eating  pigment 
in  hair  and  too  little  to  the  bacterial  flora  of  our  digestive 



tract.  Result:  fermentation,  poison,  death.  His  theory  beat 
the  gland-treatment  theory  into  the  drug  stores,  but  sour  milk 
is  losing  ground  as  a  cure  for  old  age. 

Puberty  is  a  period,  but  a  kind  of  sex  life  begins  at  birth; 
for  many,  real  sexual  maturity  never  comes.  So  it  is  with 
adults;  some  are  more  adult  in  body  and  mind  at  fifteen  than 
others  at  thirty-five;  some  hurry  through  to  senility  before 
body  and  mind  have  become  fully  adult.  Normal  old  age 
is  physiological;  it  is  no  more  a  disease  than  adolescence, 
and  should  be  as  agreeable.  In  pathologic  old  age,  senility 
is  premature  and  is  a  disease.  The  seat  of  the  disease  may 
be  anywhere  or  may  be  due  to  bacterial  infection. 

In  natural  death,  we  die  by  inches.  But  while  there  is  only 
one  path  by  which  we  may  enter  the  world,  as  Pearl  points 
out  in  his  remarkable  book  on  Death,  there  are  many  that 
lead  to  the  River  Styx.  Death  does  not  strike  at  random,  but 
in  an  orderly  way;  and  there  are  many  ways  of  dying.  We 
die  when  an  essential  part  of  our  body  breaks  down. 

From  an  analysis  of  the  mortality  tables  of  England  and 
Wales,  the  United  States,  and  Sao  Paulo,  Brazil,  Pearl  found 
that  over  half  the  deaths  in  all  three  countries  are  due  to 
faulty  wind  and  food  canals.  While  both  canals  are  inside 
the  body,  they  come  in  contact  with  air,  food,  and  water  from 
the  outside.  The  skin  also  is  exposed  to  the  world,  but  it  is 
armorplate  against  foreign  invasion.  Wind  and  food  canals 
have  no  such  protecting  layer  of  pavement  cells  as  has  the 
skin.  Outer  skin  and  lining  of  wind  and  food  canals  con- 
stitute the  body's  first  line  of  defense  against  invasion  of 

The  next  chief  cause  of  death  is  the  circulatory  system; 
the  blood  is  the  body's  second  line  of  defense.  When  the 
first  fails  to  check  the  enemy,  the  way  to  the  blood  is  open. 
Hence  the  great  part  played  by  the  circulatory  system  as  the 
second  great  cause  of  death.  As  Pearl  says,  we  should  live 
much  longer  if  our  lungs  were  as  good  as  our  heart. 

The  death  rates  show  certain  important  age  and  sex  fluctu- 



ations.  Early  infancy  deaths  are  heavy.  There  is  then  a 
sharp  drop  until  the  10-15-year  period,  when  the  rate  begins 
to  rise  to  the  20-25-year  period.  Thereafter  the  rate  rises 
slowly  until  the  50-55-year  period,  when  it  begins  to  rise 
again  rapidly. 

The  death  rate  from  failure  of  circulatory  system  rises 
steadily  from  maturity  until  the  eighty- fifth  year,  when  it 
slows  down.  But  between  the  fifth  and  thirty-fifth  years  this 
rate  is  higher  in  females  than  in  males,  presumably  because 
the  changes  accompanying  puberty  are  graver.  Up  to  the 
sixty-fifth  year  deaths  from  breakdown  of  the  sex  apparatus 
are  also  much  greater  in  females. 

The  chief  cause  of  death  among  males  during  the  first  year 
is  from  the  food  canal;  after  that,  to  the  sixtieth  year,  the 
respiratory  system;  after  the  sixtieth  year,  the  circulatory 

Nearly  60  per  cent  of  the  deaths  were  from  organs  derived 
from  the  endoderm  or  inner  germ-layer — the  layer  that  orig- 
inally was  outside  the  body.  In  the  developing  embryo  that 
layer  comes  to  be  folded  within  the  body  and  lines  the  food 
canal  and  accessory  organs  of  digestion.  It  is  an  old-fash- 
ioned, out-of-date  relic  of  antediluvian  ectoderm.  As  a  lining 
for  the  food  canal  it  is  our  weakest  spot. 

Our  strongest  spots  are  the  skin  cover  of  our  body  and  our 
nervous  system.  Both  are  derived  from  the  ectoderm  or 
outer  germ-layer.  Deaths  from  structures  derived  from  this 
layer  make  up  only  about  10  per  cent  of  the  total.  Almost 
no  germs  get  through  a  healthy  skin.  The  cells  of  skin  and 
nerves  have  differentiated  most  from  their  primitive  structure. 

The  remaining  30  per  cent  of  deaths  are  from  the  meso- 
derm or  middle  germ-layer,  circulatory  and  urogenital 
systems  and  muscles.  The  breakdown  of  the  female  repro- 
ductive organs  is  also  a  heavy  factor  in  infant  mortality. 

While  mortality  due  to  breakdown  in  ectoderm  organs  is 
about  the  same  for  the  two  sexes,  female  mortality  from 



mesoderm  is  as  great  as  from  endoderm  breakdown  twenty 
years  before  it  is  in  males. 

Death  comes,  then,  according  to  Pearl,  because  our  bodies 
are  made  up  of  systems  specialized  in  structure  and  function. 
In  becoming  specialized,  their  cells  have  become  so  differ- 
entiated that  they  have  lost  the  power  of  indefinite  and  inde- 
pendent existence.  Thus  the  cells  lining  our  lungs  can  be 
nourished  only  if  the  cells  of  the  food  tract  and  the  blood 
keep  on  the  job.  Some  systems  are  better  made  than  others. 
The  brain  outwears  the  heart,  the  heart  outwears  the  lungs. 

The  striking  agreement  as  to  the  causes  of  death  which 
Pearl  finds  in  such  dissimilar  countries  as  England,  the 
United  States,  and  Sao  Paulo,  force  him  to  conclude  that 
innate  constitutional  factors,  along  with  environmental 
factors,  largely  determine  rates  of  human  mortality.  In  cer- 
tain diseases,  of  course,  environment  is  the  important 

The  causes  of  death,  Pearl  finds,  are  in  the  following 
descending  order:  respiratory  system;  digestive  system;  cir- 
culatory system  and  blood ;  nervous  system  and  sense  organs ; 
kidneys  and  related  excretory  organs;  sex  organs;  skeletal 
and  muscular  system;  skin;  endocrine  organs.  Or,  arranged 
proportionately  according  to  embryonic  germ-layer  origin: 
endoderm  diseases  5.2  and  mesoderm  diseases  3.8  times 
those  of  ectoderm  origin. 

We  may  be  as  old  as  our  arteries — and  so  no  good  for 
digging  a  sewer;  but  we  are  also  as  young  as  our  brains — 
and  so,  good  where  brains  are  needed.  But  when  any  vital 
system  breaks  down,  the  machine  stops  and  we  are  dead. 


Medical  authorities  believe  they  could  add  thirteen  years 
to  life  if  given  full  control  in  cases  where  death  could  reason- 
ably be  prevented.  A  better  life  insurance  is  to  pick  parents 
who  will  live  to  be  eighty;  they  will  give  you  a  twenty-year 



better  hope  of  longevity  than  parents  who  will  die  under 
sixty.   They  are  the  best  life  insurance. 

Why  not?  Each  group  of  animals  has  its  normal  span 
of  life.  Also  man.  Human  beings  vary;  most  of  their 
specific  characters  are  inherited.  Longevity  is  a  specific 
character,  longevity  also  is  inherited. 

Those  who  live  to  great  age  as  a  rule  are  children  of 
parents  who  lived  to  great  age.  If  one  cannot  choose  both 
parents  who  will  live  to  old  age,  it  is  better  to  choose  a  long- 
lived  father  than  a  long-lived  mother.  Four  per  cent  more 
children  lived  to  be  eighty  where  the  father,  but  not  the 
mother,  lived  to  be  eighty,  than  where  the  opposite  condition 

Karl  Pearson  concluded  from  a  study  of  the  life  span  of 
brothers  that  environment  is  not  the  important  factor  in 
longevity;  also,  that  from  one-half  to  three-fourths  of  deaths 
are  predetermined  at  birth  by  inheritance  factors.  This  con- 
clusion has  never  been  advertised  by  health  resorts  or  elixir 

Death  rates  and  life  spans  are  but  two  phases  of  the  prob- 
lem of  longevity.  If  environment — including  health  resorts, 
elixirs,  poverty,  and  bacteria — is  not  the  factor  in  death 
rates,  it  cannot  be  the  factor  in  the  life  span. 

From  one-half  to  three-fourths  of  the  death  rate  is  selec- 
tion: death  comes  when  one  has  used  up  one's  inherited 
capacity  for  life.  Adults  of  sound  body  are  more  likely  to 
leave  offspring  than  those  of  weak;  their  children  are  more 
likely  to  survive.  Weaklings  may  survive  to  maturity,  their 
children  are  less  likely  to  survive. 

Hence  the  high  infant  death  rate  in  the  first  two  years; 
the  unfit  are  weeded  out.  Natural  Selection  is  still  at  work; 
it  has  always  been  at  work.  This  rate  is  especially  high 
among  children  of  unsound  parents.  Hygiene  and  prevention 
lower  the  rate  during  these  two  dangerous  years — ^prolonging 
lives  to  succumb  at  a  later  but  early  stage. 

A  banana  fly  of  ninety  days  is  as  old  as  a  man  of  ninety 



years.  Twenty-four  hours  after  emerging  from  the  pupa 
stage,  the  female  fly  lays  eggs.  These  in  one  day  become 
larvae,  pupae  three  days  later,  adults  five  days  later;  ten  days 
to  a  generation.  Pearl  tested  the  life-span  inheritance  theory 
on  these  flies.  More  females  than  males  survived — as  in 
man.  The  only  fly  that  lived  to  be  eighty-one  days  old  was  a 
female.  Long-lived  parents  bred  off'spring  that  lived  long. 
Pearson  was  right:  duration  of  life  is  an  inherited  character. 

How  about  germs  of  diphtheria,  tuberculosis,  etc.?  Loeb 
tested  this  on  flies,  with  the  surprising  result  that  those  kept 
free  from  bacteria  were  possibly  shorter-lived  than  germ- 
laden  flies,  certainly  no  longer.  The  experiments  indicated 
"that  higher  organisms  must  die  from  internal  causes  even 
if  all  chances  of  infection  and  all  accidents  are  excluded." 

We  are  never  without  bacteria;  we  could  not  live  without 
them;  there  is  no  habitable  spot  on  earth  free  of  them.  Of 
humans  who  have  reached  the  thirty-fifth  year,  95  per  cent 
have  been  infected  at  one  time  or  another  with  the  bacillus 
of  tuberculosis ;  in  less  than  one  in  ten  does  it  become  active. 

Death  rates  in  the  poverty  lanes  of  Paris  and  London  do 
not  tally.  In  Paris  the  excess  death  rate  in  the  poorest  as 
against  the  richest  quarter  is  104  per  cent;  in  London,  only 
30.  The  lowest  death  rate  in  London  is  not  in  the  richest 
quarter.  The  real  influence  of  poverty  on  death  rates  could 
only  be  determined  by  transposing  the  inhabitants  of  the  two 
groups  and  comparing  rates.  The  "poor"  of  Paris  and 
London  are  not  necessarily  biologically  poor. 

It  is  the  pace  that  kills.  "General  Sherman,"  the  giant 
redwood,  was  killed  at  the  age  of  2,171  years.  He  was  a 
seedling  in  271  B.  C.  He  never  knew  what  hurry  meant. 
Nor  did  the  tortoise  that  lived  350  years.  The  faster  we 
live,  the  sooner  we  live  life  up.  Rate  of  living  is  a  factor 
in  longevity.  Slonacker  tested  this  on  rats.  He  put  four  in 
squirrel  cages  and  let  them  race.  The  average  life  span  of 
the  marathoners  was  29.5  months;  one  lived  thirty-four 
months  and  ran  5,447  miles.    Three  other  rats  were  reared 



in  squirrel  cages,  but  were  not  permitted  to  race;  their 
average  span  was  48.3  months. 

Loeb  tried  flies.  Cold  makes  flies  sluggish;  those  at  cold 
temperature  lived  longer  than  those  at  high.  At  86  degrees, 
his  flies  lived  21  days;  at  68  degrees,  54  days;  at  60  degrees, 
124  days.  From  which  he  inferred  that  if  we  could  keep 
our  blood  temperature  at  about  45  degrees,  we  might  hope 
to  live  about  1,900  years.    But  life  would  be  at  a  low  level! 

Unfortunately,  our  early  ancestors  left  no  trustworthy  vital 
statistics.  But  from  trustworthy  inferential  data  there  is 
reason  to  believe,  as  we  might  expect  on  purely  biologic 
grounds,  that  longevity  is  on  the  increase.  At  least,  life 
expectancy  has  improved  during  the  last  2,000  years.  Of 
100  Romans  born  in  Egypt  in  the  days  of  the  Empire,  only 
9  could  expect  to  live  68  years.  Of  100  English  alive  at 
10,  39  live  to  be  68.  Women  especially  had  less  expectancy 
of  life  in  Roman  days  than  now — they  were  in  luck  to  be 
alive  at  25.  But  a  Roman  of  78  years  was  a  better  risk  than 
an  American  of  the  same  age;  a  Roman  had  to  be  very  hardy 
to  live  beyond  70.  In  America,  many  weaklings  are  carried 
up  to  60;  beyond  that  age  their  expectancy  rapidly 

From  which  we  conclude  that  modern  environment  is 
better  for  man,  or  that  man  is  fitter  for  modern  environment. 


Life  goes  on:  only  individuals  die.  Some  individuals 
apparently  are  also  endowed  with  immortality — such  are  the 
Protozoa  or  one-cell  organisms.  Nearly  all  Metazoa  or 
many-cell  organisms  die — their  endowment  is  mortal. 

Man  also  is  a  Metazoon.  All  men  die.  Must  they  die? 
Until  recently  this  would  have  been  a  foolish  question.  It 
cannot  yet  be  answered,  but  experiments  now  going  on  for 
twenty- five  years  give  us  food  for  thought. 

Since  boys  have  been  boys  it  has  been  known  that  the 



snake's  tail  does  not  die  until  the  sun  goes  down.  For  ages 
it  has  been  well  known  that  many  animals  have  the  power 
to  grow  certain  missing  parts.  A  fish-worm  cut  in  two  grows 
into  two  worms — the  head  grows  a  tail,  the  tail  a  head.  Cut 
a  crab's  eye  from  its  stack,  it  grows  another  eye  just  as  good. 
Cut  a  leg  from  a  crayfish,  it  grows  another  leg.  Cut  a  finger 
off  the  human  hand ;  no  finger  grows  on.  But  our  hair  keeps 
on  growing;  it  may  grow  even  after  the  last  heartbeat.  Cut 
a  nerve  fiber  of  a  finger;  the  fiber  "dies"  from  the  point 
where  cut  to  the  end  of  the  finger  and  so  paralyzes  that  end 
of  the  finger.  But  the  live  end  begins  to  grow  again  and 
finally  reaches  the  end  of  the  finger.  Even  though  the  finger 
had  been  mangled,  the  nerve  finds  its  way,  if  it  has  to  go 
around  bone  and  muscle.  At  the  end  of  its  journey  it  stops 
growing;  the  finger  is  no  longer  paralyzed. 

In  1907  Leo  Loeb  informed  the  world  that  he  was  growing 
frog  nerve  in  a  glass  jar.  Biologists  began  to  grow  pieces  of 
tissue  from  other  animals  in  glass  jars.  Wilson  chopped  up 
a  sponge  and  squeezed  the  pieces  through  close-woven  cloth 
to  separate  its  cells.  He  "cultivated"  one  cell;  it  grew  into 
a  whole  sponge.  Carrel  cultivates  all  sorts  of  adult  tissue 
in  glass  jars;  even  cancer  cells.  He  has  cancer  cells  that 
have  outlived  several  hosts.  He  cut  a  piece  from  the  embryo 
of  a  chick;  after  nine  years  it  was  still  alive  and  growing. 
He  cut  muscle  cells  from  a  chick  embryo's  heart;  they  grow 
and  beat. 

That  opened  the  coffin  again.  Tissues  cut  from  living 
bodies,  it  was  thought,  should  not  grow,  they  should  die! 
They  are  not  ger/Ti-cells,  they  are  only  body  or  5077ia-cells. 
Soma  cells  were  not  supposed  to  be  endowed  with  immor- 
tality. Yet  under  cultivation  they  live,  they  multiply,  they 
grow.    In  a  jar. 

Soma  cells  also  are  potentially  immortal! 

Then  why  do  they  die?  Why  is  our  saliva  full  of  dead 
cells  and  the  skin  of  our  body  covered  with  dead  cells?  WTiy 
is  the  body  that  was  living  now  dead? 



What  is  death?  No  one  yet  knows.  No  one  knows  what 
life  is.  We  only  know  the  living  from  the  dead.  We  know 
more  about  the  causes  of  death  than  we  did.  But  are  we 
checking  disease,  postponing  death?  Can  we  renew  our 
youth?  Are  we  about  to  make  death  merely  an  accident? 
Can  we  synthesize  life?  Man  by  nature  is  not  too  modest, 
nor  by  training  without  hope  or  the  habit  of  stretching  his 
imagination.  Our  answer,  then,  is,  "Yes,  why  not?"  And 
a  pleasant  time  is  had  by  all.  Molasses  catches  more  flies 
than  vinegar. 

Such  important  functions  of  our  body  as  heartbeat,  breath- 
ing, digestion,  and  absorption  are  beyond  the  control  of  our 
wills;  they  have  their  own  centers  or  systems  of  control.  We 
do  not  even  yet  know  where  all  these  centers  and  systems 
of  control  are  located. 

When  we  know  just  what  takes  place  when  a  sweet  becomes 
a  sour,  or  how  a  cell  converts  sugar  into  glycogen,  or  why 
a  heart  beats  in  a  certain  solution  and  stops  dead  if  the 
acidity  of  that  solution  is  increased  by  one  billionth  part,  we 
can  begin  to  talk  about  prolonging  life. 

Not  one  single  process  that  goes  on  in  any  one  cell  of  our 
body  has  yet  been  completely  analyzed.  When  some  of  the 
processes  of  life  have  been  even  fairly  well  analyzed,  it  will 
be  possible  to  speak  of  the  artificial  synthesis  of  life. 

Nevertheless,  there  is  every  reason  to  believe  that  we  may 
look  forward  to  a  greatly  increased  control  over  evolutionary 
processes.  Why  not?  Think  of  the  already  enormously 
increased  ability  to  control  growth  in  living  organisms.  This 
control  has  only  come  with  an  understanding  of  the  nature 
of  the  stuff  of  organisms  in  which  energy  is  transformed,  and 
of  the  relation  of  organisms  to  the  external  world.  With 
wider  understanding  will  come  wider  control.  But  progress 
must  be  slow,  because,  as  Child  warns  us,  we  deal  with 
internal  conditions  which  are  the  result  of  millions  of  years 
of  alternating  change. 

It  is  all  so  new.   There  are  to-day  a  half-dozen  flourishing 



sciences  devoted  to  the  study  of  life  where  a  few  years  ago 
there  was  not  one.  For  the  first  time  in  human  history  man 
has  trained  his  new-found  instruments  of  precision  on  newly 
conceived  problems.  He  can  at  last  ask  questions  about 
himself  and  about  life  in  general.  Direct  questioning  has 
replaced  vague  and  childish  speculation.  Problems  have 
been  formulated  and  solved.  And  every  problem  solved  has 
opened  wider  vistas — and  more  problems.  But  no  problem 
was  ever  solved  by  propaganda.  Nor  is  disease  checked  by 
mere  optimism — though  digestion  can  be  checked  by  a  bill 
collector  and  a  mouse's  heartbeat  increased  from  175  to  600 
per  minute  by  a  mouse  trap. 

The  death  rate  is  declining;  it  has  been  declining  for 
centuries.  Men  born  to-day  can  expect  longer  life  than  men 
born  twenty,  fifty,  five  hundred,  or  five  thousand  years  ago. 
Why  this  is  so  is  not  at  all  well  understood.  The  decline  in 
death  rate  in  modern  times  is  as  true  of  "backward"  countries 
as  it  is  of  Germany,  England,  the  United  States.  The  drop 
is  also  as  true  of  the  non-preventable  diseases  as  of  those 
which  are  supposed  to  be  subject  to  control. 

The  part  that  health  officers,  etc.,  play  in  this  decline  is 
uncertain.  War  has  been  increasingly  waged  against  tuber- 
culosis for  nearly  a  century;  the  tuberculosis  rate  has  dropped 
less  than  that  for  diphtheria,  croup,  typhoid,  and  dysentery. 

The  cause  of  many  diseases  is  yet  unknown,  of  others  only 
partially  surmised.  Man  responds  to  his  environment,  as 
does  all  life;  but  he  is  changing  his  environment,  in  places  at 
an  extraordinarily  rapid  rate.  What  is  the  result  or  what 
will  be  the  result  of  these  changes  is  not  yet  known,  nor  can  it 
be  predicted  with  any  degree  of  certainty. 

We  hand  public  health,  as  we  do  government,  over  to  a 
power  which  we  expect  thereafter  to  run  of  its  own  accord. 
But  neither  ever  gets  very  far  ahead  of  the  load  it  is  supposed 
to  carry.  Meanwhile,  for  every  one  that  knows  what  to  eat 
and  why,  there  are  a  hundred  who  eat  for  their  tongue's  sake 
and  let  it  go  at  that,  not  knowing  that  a  double  chin  may  be 



a  misdemeanor  or  that  arteries  and  nerves  may  be  as  easily 
choked  in  fat  as  a  cat  with  butter.  Many  use  their  body  as 
a  clothes  horse  and  are  only  concerned  with  the  parts  that 

Startling  facts  come  from  physiological  laboratories.  They 
force  us  to  revise  our  conceptions  of  life  and  death,  of  youth 
and  old  age.  All  protoplasm  is  potentially  immortal.  Man 
is  protoplasm.  Hence  .  .  .  But  Man  is  highly  complex  pro- 
toplasm— an  organism  of  infinite  complexity,  of  tissues  and 
organs  and  systems  greatly  differentiated,  some  more,  some 
less.  This  mass  of  protoplasm  functions,  lives,  because  these 
parts  work  together  for  a  common  end.  They  are  marvel- 
ously  balanced.  Upset  the  balance:  disease;  if  the  balance 
cannot  be  restored,  the  machine  is  broken.  A  few  minor  parts 
may  be  restored;  a  few  may  be  dispensed  with.  The  machine 
breaks  when  a  vital  part  breaks.    It  never  runs  again. 

Isolate  the  liver  or  one  brain  cell  and  study  it  a  lifetime: 
liver  as  function  and  cell  as  behavior  are  as  meaningless  and 
as  lifeless  as  a  last  year's  bird  nest.  The  parts  of  the  human 
body  are  meaningless  in  and  by  themselves.  Put  some  cells 
in  a  glass  jar  and  watch  them  grow.  Where  does  this  land 
us?  Those  cells  are  immortal — in  "proper  medium." 

Each  of  the  billions  of  cells  in  the  human  body  must  also 
be  kept  in  proper  medium.  Those  cells  themselves  are  the 
medium.  On  their  own  shoulders  rests  the  burden  of  keeping 
that  medium  proper;  they  and  they  alone  can  right  the 
machine,  they  and  they  alone  know  the  levers.  If  they  can- 
not reverse,  there  comes  a  crash.   The  machine  is  broken. 

Nothing  yet  has  come  from  the  laboratory  to  give  us  hope 
that  the  crash  is  not  inevitable.  All  vital  processes  are  re- 
versible; they  must  be.  To  live  is  to  keep  making  compen- 
sations: changes,  backward  and  forward.  Simple  organisms 
have  it  in  themselves  to  make  these  compensations;  they  have 
their  dynamic  equilibrium  in  their  own  hands,  as  it  were. 

Man  does  not:  it  is  the  price  he  pays  for  hands.  Hands 
wear  out.    Even  brain  cells.    We  cannot  grow  new  hands 



or  new  brains.  They  grow  up  together,  though  of  different 
heritage,  the  brain  being  far  more  ancient,  hence  more  en- 
during. They  live  together:  a  pin-prick  on  the  finger  may 
be  the  death  of  the  brain. 

The  break  may  come  from  within,  or  from  without,  or  from 
any  one  of  a  vast  number  of  causes.  Three  out,  all  out.  So 
in  the  game  of  life.  The  number  of  our  outs — or  innings — 
is  set  in  our  inheritance  and  buried  from  sight  in  the  complex 
mechanism  which  is  ours  for  a  while.  We  can  burn  it  up  or 
jolly  it  along.  But  beyond  a  certain  point  there  seems  to 
come  a  limit  to  its  mileage.  The  machine  wears  out  because 
it  is  that  kind  of  a  machine.  It  dies  because  sooner  or  later 
the  Marksman  of  Death  strikes  a  vital  spot. 

Pearson  in  his  Chances  of  Death  pictures  a  Bridge  of  Life 
across  which  is  a  trickle  of  humanity.  They  are  under  the 
fire  of  the  five  Marksmen,  one  for  each  Age.  They  fire  with 
different  weapons,  speeds,  and  degrees  of  precision.  The 
first  Marksman  concentrates  a  deadly  fire  upon  Infancy — 
before  as  well  as  after  birth;  "beating  down  young  lives  with 
the  bones  of  their  ancestors."  The  second  Marksman  aims 
a  machine-gun  at  Childhood;  his  fire  is  concentrated,  the 
loss  is  less  appalling.  The  third  shoots  at  Youth  with  a  bow 
and  arrow;  there  is  no  great  loss.  The  fourth  fires  slowly  at 
Maturity  with  a  blunderbuss;  his  hits  are  scattered.  The 
fifth  Marksman  of  Death  is  a  sharpshooter;  no  one  can  escape 
the  Death  of  Senility. 




I.  The  Old  and  the  New  Psychology.  2.  The  Impulse  to  Live.  3.  Samples 
of  Low  Life  Behavior.  4.  The  Animal  "Mind."  5.  The  Excitability  of  Living 
Matter.  6.  The  Nature  of  the  Reflex  Arc.  7.  The  "AU-or-None"  Conductors. 
8.  Reflex  Action.    9.  The  Nature  of  Nerves.    10.  The  World  as  Stimulus. 

II.  Receptors  of  Sights  and  Sounds.  12.  Receptors  of  Chemical  Stimuli, 
13.  Visceral  and  Kinesthetic  Receptors.  14.  The  Nervous  System.  15.  The 
Lower  Centers  of  the  Nervous  System.  16.  The  Supreme  Adjustor.  17.  The 
Pictured  Movements  of  the  Brain.  18.  The  Conditioned  Reflex.  19.  The 
Autonomic  Nervous  System.  20.  Cramps  and  Fatigue.  21.  Mind  and 


Of  all  the  'ologies  I  studied  in  school,  the  one  that  gave  me 
the  least  light  on  man  and  myself  was  psychology — excepting, 
possibly,  mineralogy.  It  worried  me :  I  wanted  to  learn  about 
my  own  and  man's  psyche,  and  did  not.  I  assumed  it  was 
because  the  course  was  over  my  head.    It  was. 

For  this  reason.  To  the  old  psychology  heads  were  like 
crystals.  By  gazing  into  them,  called  "introspection,"  the 
mind  could  be  seen  and  studied.  Crystal-gazing  never  did 
call  itself  a  science;  mind-gazing  did,  but  is  now  also  only  a 
cult.  The  introspectors  could  not  agree  as  to  what  they  saw. 
But  that  they  were  looking  at  "mind"  they  had  no  doubt. 
Their  logic  was  simple  and  convincing:  mind  is  not  matter, 
the  body  is  matter;  mind  and  body,  therefore,  are  separate 
and  distinct  entities.  They  turned  the  body  over  to  sawbones 
and  kept  "mind"  for  themselves  and  went  on  arguing  about 
what  they  saw  in  it. 

"I  see  red,"  says  one.  "Is  it  pure?"  asks  another;  "is  it 
perception,  sensation,  connotation,  or  ideation;  or  is  it  a 



conception,  or  the  imagination?  Is  it  as  content,  awareness, 
or  as  ego?  If  as  ego,  can  you  time  it;  if  as  awareness,  can 
you  weigh  it?"  This  is  all  nonsense,  of  course;  but  not  more 
so  than  the  psychology  I  studied  in  school. 

The  net  result  of  introspection  was  a  Noah's  Ark  of  stalls 
each  labeled  for  an  occupant,  a  "content  of  the  mind."  It 
was  not  unlike  the  shaved-head  phrenology  charts  with  allotted 
areas  for  bumps  of  amativeness,  adhesiveness,  philoprogeni- 
tiveness,  and  other  faculties.  Phrenology  broke  down  before 
the  fact  that  my  bump  of  "amativeness"  may  be  due  to  a 
thick  skull,  water  beneath  the  skull,  or  the  fact  that  with  no 
bump  at  all  I  am  very  amative. 

The  old  psychology  went  the  same  way.  Mind  was  found 
to  be  neither  a  "secretion  of  the  brain"  as  bile  is  of  the  liver, 
nor  any  thing  or  process  apart  from  a  living  body.  It  was 
next  discovered  that  the  brain  itself  is  simply  a  part  of  the 
central  nervous  system,  the  body's  integrating  organ  or 
mechanism  of  adjustment.  That  this  mechanism  is  born 
primed  for  many  primitive  naked-and-unashamed  activities, 
but  is  unlearned  in  modern  ways  and  learns  only  by  expe- 
rience, was  the  next  step  in  the  downfall  of  the  old  ps)^- 

With  the  realization  that  some  individuals  have  no  mind  at 
all,  individual  behavior  began  to  be  a  problem.  With  the 
realization  that  the  outstanding  fact  of  evolution  is  individual 
variation,  and  that  the  significant  fact  of  the  genus  Homo  is 
individual  behavior,  and  that  stereotyped  behavior  in  an  in- 
dividual is  a  sign  of  abnormality  and  if  vicious  lands  him 
in  a  padded  cell,  the  old  science  of  mind-gazing  lost  its  pep 
and  the  gazers  began  to  try  to  find  out  what  happens  to  human 
beings  and  why.  And  that  is  a  real  problem,  from  the  com- 
plete solution  of  which  we  are  yet  miles  and  years. 

To  solve  a  problem  is  to  know  its  laws.  To  know  the  laws 
is  to  be  able  to  make  predictions.  For  example:  I  can  pre- 
dict the  behavior  of  a  pint  of  ethyl-alcohol  under  many  physi- 
cal and  chemical  changes  so  accurately  that  you  can  expect 



your  pint  of  C2H5OH  to  behave  the  same  way  under  the  same 
conditions.  That  is  science.  I  cannot  predict  your  behavior 
when  you  drink  that  pint  of  alcohol — the  personal  equation 
is  too  big. 

Sciences  are  exact  to  the  extent  that  the  personal  equation 
is  eliminated.  The  personal  equation  can  never  be  eliminated 
in  predicting  human  behavior. 

General  predictions,  yes.  Cats  are  cats,  dogs  are  dogs, 
pigs  are  pigs.  No  two  alike,  but  enough  alike  for  practical 
purposes.  Can  you  predict  any  certain  tomcat's  behavior 
an  hour  hence?  You  cannot  even  predict  next  week's  weather. 
A  three-year-old  child  contains  more  elements  than  the 
weather  and  is  driven  by  more  forces.  Can  you  predict  its 
behavior?  The  particular  behavior  of  any  one  human  being 
under  any  one  certain  condition  may  depend  on  an  infinitesi- 
mal amount  of  a  hormone  yet  unknown  to  science.  Give  up? 
No ;  look  into  hormones,  into  individual  inheritance,  into  mil- 
lions of  reflexes  many  of  which  may  be  put  out  of  action  by 
the  wink  of  an  eye.  What  is  the  nature  of  hormones,  what  is 
it  that  is  inherited,  how  are  reflexes  conditioned  and  acquired, 
how  are  they  put  out  of  action,  why  can  a  wink  be  so  devas- 

Man  both  makes  and  outlaws  his  own  laws.  He  cuts  off" 
his  nose  to  spite  his  face;  dies  to  live  and  makes  a  martyr  of 
himself  in  the  name  of  custom;  scarifies  his  face  and  body, 
deforms  his  head,  waist,  and  feet,  and  wears  sackcloth  and 
ashes,  patent-leather  shoes,  and  plug  hats  in  the  name  of 
fashion;  and  consigns  to  hell  his  infants'  souls  in  the  name  of 
the  Saviour  he  implores  to  save  his  own  soul. 

The  vagaries  of  human  behavior  seem  as  countless  as  the 
sands  of  the  sea;  but  the  sands  can  be  classified  and  described. 
Human  behavior  also,  though  the  problem  is  more  complex 
and  shifting.  That  man  makes  an  ass  of  himself  and  elects 
himself  a  saint  only  adds  zest  to  the  study  of  human  behavior. 
Man  is  not  only  the  most  curious  thing  in  the  world,  but  the 



most  interesting,  not  only  to  live  with,  but  as  an  object  of 

The  old  psychology  died  hard ;  it  has  not  been  easy  to  give 
up  mental  faculties.  But  in  surrendering  mind  to  philosophy 
we  have  gained  living  human  beings;  in  abandoning  the 
search  for  some  magic  power  to  transform  human  nature  we 
have  discovered  how  to  transmute  "imps  into  angels  by  the 
alchemy  of  smiles." 

Not  that  we  are  born  imps,  but  helpless  infants  with  a 
specific  nature  called  human  and  a  definite  equipment  for 
learning  human  and  inhuman  behavior.  This  inheritance 
makes  up  the  raw  materials  of  the  new  psychology.  What  is 
its  nature,  how  is  it  modified  by  nurture?  These  two  problems 
resolved,  the  new  psychology  can  begin  to  formulate  the  laws 
and  principles  which  govern  human  reactions,  in  individuals, 
in  groups,  in  nations.  When  that  time  comes — and  it  will — 
it  will  be  possible  so  to  organize  human  affairs  and  human 
society  that  the  innate  love  for  life  can  find  satisfaction  in 
loyalty  to  ideals  and  service  to  humanity. 


Everything  cuts  up  or  behaves:  electrons,  atoms,  ions,  mole- 
cules, water,  gunpowder,  living  beings,  everything.  We  can 
know  things  only  by  their  behavior.  Living  things  have  their 
own  modes  or  ways  of  behavior;  there  are  certain  criteria  of 
livingness.  Among  these  criteria  is  growth  in  a  complex  dy- 
namic protoplasmic  mechanism.  Such  a  mechanism  cannot 
grow  without  energy.  This  energy  comes  primarily  from 
the  sun;  the  earth  itself  is  the  source  of  the  protoplasm. 

The  living  organism  thereby  called  to  life  came  at  last  to 
be  born  of  woman.  From  the  beginning  of  its  individual  ex- 
istence as  a  fertilized  ovum  until  senile  decay  and  death 
exhaust  its  inherited  potentialities  and  complete  its  living 
cycle,  it  never  stops  growing,  although  it  does  stop  growing 
larger.   This  growth  or  change  of  body  during  the  life  cycle 



is  one  aspect  of  human  Hfe:  genetic  behavior  or  morphology. 

During  life  certain  vital  processes  take  place  in  glands  and 
organs  of  digestion,  circulation,  respiration,  etc.,  whereby 
the  growth  of  the  body  is  regulated  and  the  individual  is 
maintained  in  health.   This  is  visceral  behavior. 

The  third  aspect  of  behavior  includes  the  responses  where- 
by the  individual  is  adjusted  to  the  outside  world.  These 
responses  are  generally  made  with  the  motor  mechanism  of 
the  body  and  involve  locomotion  or  speech,  and  hence  are 
called  somatic  behavior,  or  psychology. 

But  note  that  all  forms  of  behavior  of  all  living  things 
have  a  common  origin,  spring  from  a  common  root,  and  obey 
the  same  fundamental  laws  of  life.  Hence  every  phase  of 
human  behavior  is  but  part  of  the  problem  of  life  in  general 
— and  every  problem  of  life  involves  all  of  life  and  the 
environment  of  life.  The  uniqueness  of  life  is  the  way  living 
beings  respond  to  vital  stimuli,  thereby  so  adjusting  them- 
selves that  they  continue  their  existence  as  living  beings. 
Therein  lies  the  uniqueness  of  life.  To  say,  with  Herbert 
Spencer,  that  life  corresponds  with  environment  is,  as  Herrick 
points  out,  to  advance  life  no  further  than  a  self -registering 
thermometer.  The  thermometer  reacts  to  an  outside  stimulus; 
the  stimulus  is  an  impinging  energy.  But  life  not  only  wars 
against  disintegrating  agents,  "it  captures  the  attacking  forces, 
appropriates  their  base  of  supplies,  and  compels  the  hostile 
phalanx  actually  to  turn  about  and  fight  the  battles  of  the  tri- 
umphant organism." 

Why  this  unique  behavior  of  living  things?  It  is  their 
nature;  that  kind  of  behavior  is  inherent  in  living  protoplasm. 
Because  of  its  nature,  it  adjusts  itself  to  its  environment. 
It  eats,  it  excretes;  it  derives  energy  from  food,  it  is  driven 
by  energies  which  impinge  upon  its  body.  Some  of  that 
energy  is  dissipated  in  heat  and  in  energy-consuming  activities 
inside  its  body;  some  of  that  energy  is  stored  within  its  body; 
some  of  that  energy  is  expended  in  waiting  for  or  going  after 



more  energy.  These  are  all  vital  processes  and  consume 
energy  for  vital  adjustments. 

"Vital"  is  a  useful  word  and  cloaks  much  that  is  yet  in- 
scrutable. But  the  energy  with  which  you  hold  this  book  is 
but  the  energy  of  your  impinging  environment  so  combined 
with  the  energy  within  you — orginally  won  from  nature  by 
plants — and  so  transformed  in  you  into  such  a  high  potential 
current  that  it  can  be  made  to  do  such  work  as  human 
machines  are  by  their  nature  and  training  impelled  to  do. 

Living  impulses,  vital  adjustments;  the  call  to  live,  the 
response  to  the  call;  the  living  being  as  an  individual;  the 
reactions  of  the  individual  living  human  being:  these  matters 
are  now  our  concern.  But  again  let  it  be  said  that  any 
psycho-analysis  which  neglects  the  facts  of  genetic  and  vis- 
ceral behavior  will  never  discover  the  materials  with  which 
to  synthesize  a  human  being.  Human  psychology  is  rooted  in 
living  human  protoplasm  and  can  be  explained  only  in  terms 
of  its  antecedent  history. 


The  pyschology  of  bacteria  is  not  well  known  because  they 
have  only  recently  been  discovered.  But  the  lowest-lived 
bacteria  known  to  the  microscope  make  distinctions  that 
baffle  the  biochemists  who  study  them.  They  have  an  astound- 
ing capacity  to  transform  energy  and  they  are  sensitive  to 
extraordinarily  minute  stimuli.  Their  behavior  can  only  be 
described  in  physico-chemical  terms. 

Some  bacteria  produce  light.  Do  they  burn  luciferin? 
Do  they  use  the  enzyme  lucif erase  as  catalyzer?  Fireflies  do, 
and  have  special  organs  for  its  manufacture.  These  organs 
are  controlled  by  nerves  and  respond  to  certain  stimuli;  and 
they  all  light  up  at  once!  Firefly  behavior  can  be  talked  about 
in  psychologic  terms,  but  such  terms  tell  us  nothing  of  the  life- 
light  of  the  light-producing  bacteria  that  cause  decaying  wood 
and  flesh  to  glow.   The  psyche  of  bacteria  is  physics. 



Animals  are  fond  of  sugar.  There  are  hundreds  of  sugars; 
some  are  so  much  alike  that  man  cannot  tell  which  is  which. 
Bacteria  can.  They  can  detect  a  thousandth  part  of  1  per 
cent  of  certain  sugars;  they  prove  it  by  their  behavior.  Are 
they  on  speaking  terms  with  atoms?  At  any  rate,  their  reac- 
tions are  more  refined  than  those  of  the  sugar  chemist's  re- 
agents. And  yet  bacteria  are  so  low  that  science  has  not  yet 
decided  that  they  are  real  cells.  But  they  are  alive;  they  re- 
spond to  stimuli  and  run  the  gamut  of  adjustment  behavior 
on  which  life  depends. 

Animal  adjustment  generally  involves  locomotion.  Low 
forms  flow,  because  life  is  fluid.  The  solidity  of  bones, 
horns,  teeth,  hair,  etc.,  is  due  to  dead  mineral  matter  between 
living  cells,  as  is  the  "wood"  of  trees.  White  blood-cells 
flow  through  membrane.  Certain  Protozoa  that  live  on  moldy 
wood  can  flow  through  cotton  mesh  so  fine  as  to  strain  the 
food  from  their  body.  Once  through,  the  streams  of  proto- 
plasm unite  again  into  a  single  body  which  behaves  as  though 
it  had  not  been  strained.  By  such  streaming  movements 
amebae  and  white  blood-cells  ingest  food  particles  by  flowing 
around  them. 

A  worm  has  been  seen  under  the  microscope  to  swim 
through  the  protoplasm  of  a  frog's  muscle,  the  protoplasm 
closing  behind  the  worm.  At  one  point  the  frog's  muscle 
had  been  injured — it  was  "dead";  the  worm  could  not  swim 
through  that,  it  went  around  it  as  though  it  were  a  stone. 

Because  of  this  fluidity,  living  protoplasm  can  respond. 
Without  fluidity,  muscles  could  make  no  response.  Cutting 
a  nerve  paralyzes  a  muscle  but  does  not  kill  it,  though  disuse 
will  cause  it  to  waste  away.  Every  living  muscle-cell  can 
respond  to  stimulus. 

The  microscopic  cilia  lining  our  windpipe  move  in  defi- 
nite rhythmic  sequence,  wave  after  wave,  like  a  field  of  wav- 
ing grain.  A  speck  of  dust  excites  them  to  move;  the  larger 
the  speck,  the  faster  they  move.  Cilia  are  ancient  structures, 
the  sole  motor  mechanism  of  many  micro-organisms.  Could 



we  get  as  much  work  out  of  our  motor  apparatus  as  the  little 
Paramecium  does  with  its  cilia,  we  could  lift  1,500  pounds. 
Cilia  cut  from  a  frog's  throat  keep  right  on  moving;  they 
will  work  a  weight  uphill. 

Bacteria,  amebse,  white  blood-cells,  muscle-cells,  ciliated 
cells,  are  all  types  of  behavior,  samples  of  life's  adjustments 
to  livable  conditions.  Every  living  cell  and  every  living  or- 
ganism, from  yeast  to  man,  has  its  own  reaction  system,  its 
own  type  of  behavior;  its  own  psyche — if  you  like  that  word. 


Washburn's  Animal  Mind,  second  edition,  lists  841  titles 
consulted  in  the  preparation  of  her  book.  That  was  eight 
years  ago.  The  next  edition  will  probably  list  a  thousand 
titles;  shall  we  know  more  then  about  the  "mind"  of  animals? 

Can  the  mind  be  seen?  Why  not.  We  "see"  metabolism, 
and  know  much  of  the  processes  of  chemical  exchange  be- 
tween living  organisms  and  their  environment.  We  call  these 
exchanges  physiological  processes;  and  while  there  are  many 
that  are  only  partly  understood,  and  many  that  are  as  yet 
only  partially  guessed  at,  no  one  speaks  of  physiological 
processes  with  furrowed  brow,  unless,  indeed,  the  process 
at  the  time  is  functioning  badly.  But  "mind"  suggests  mys- 
teries, vague  realms  in  which  souls  converse  with  souls  and 
psychic  phenomena  defy  every  known  or  conceivable  law  of 
matter  and  energy. 

Mind  is  not  matter;  neither  is  the  attraction  of  the  positive 
half  of  the  magnet  for  molecules  of  potassium  and  sodium, 
matter.  But  the  attraction  of  an  anode  for  potassium  and 
iron  filings  is  a  relation  between  matter.  Certain  elements 
are  attracted  by  an  anode,  some  are  repelled;  a  youth  is 
attracted  by  a  maiden.  There  the  matter  is;  it  is  open  to  in- 
vestigation. The  "matter"  may  be  a  wisp  of  hair  or  a  down- 
cast eye. 

Mind  is  like  life:  it  is  known  only  by  the  company  it  keeps, 



living  organisms;  they  are  real.  There  are  criteria  for  liv- 
ingness.  They  often  fail.  An  organism  may  show  no  signs 
of  life:  as  an  opossum,  or  a  grain  of  wheat.  Is  it  alive? 
Only  by  applying  certain  stimuli  can  we  tell.  If  it  makes  no 
response,  it  is  dead.  "Certain  stimuli":  what?  Stimuli  known 
to  be  harmful  to  opossum  or  vital  for  wheat  germs. 

The  live  grain  germinates  under  proper  stimuli.  Its  be- 
havior can  be  observed  and  described  in  terms  of  energy  and 
matter,  and  in  its  behavior  will  be  found  no  contradiction  to 
the  laws  of  physics  and  chemistry.  That  germinating  grain 
shows  behavior;  it  has  no  mind,  of  course?  Plant  physiolo- 
gists are  not  so  certain;  some  are  quite  certain  that  if  an 
ameba  has  a  "mind,"  a  grain  of  wheat  has. 

Has  the  ameba  a  mind?  But,  first,  what  is  mind:  con- 
sciousness? reason?  intelligence?  intellectual  faculties?  Or 
all  these  combined?  I  may  think  I  know  what  is  on  my  mind 
and  what  my  mind  is.  How  can  I  know  your  mind?  I  look 
at  a  picture:  I  know  what  I  see;  I  know  the  emotions,  mem- 
ories, etc.,  the  picture  rouses  in  me.  I  cannot  know  what  that 
picture  is  to  you  except  by  your  behavior :  words,  actions,  etc. 
Even  then  I  must  interpret  your  behavior  in  terms  of  my 
own  experience.  There  may  be  nothing  in  my  experience 
which  gives  me  a  clue  to  your  behavior. 

When  Washburn  says  that  we  know  that  consciousness — 
"as  evidence  of  mind" — resides  in  ourselves,  that  it  undoubt- 
edly exists  in  animals  with  structures  resembling  ours,  and 
that  "beyond  this  point,  for  all  we  know,  it  may  exist  in 
simpler  and  simpler  forms  until  we  reach  the  very  lowest  of 
living  beings,"  I  do  not  see  that  she  has  moved  either  forward 
or  backward.  To  say  even  that  mind  is  a  quality  of  living- 
ness,  a  sign  of  life — as  is  oxidation  a  sign  of  metabolism — 
is  probably  quite  as  futile.  To  say  that  one  ameba  engulf- 
ing another  is  a  sign  of  hunger,  a  spitfire  cat  with  an  arched 
back  and  slashing  tail  a  sign  of  anger,  a  dog  with  a  can  tied 
to  its  tail  yelping  down  the  street  a  sign  of  fear,  and  a  strutting 



cock  a  sign  of  amorousness,  is  to  anthropomorphize  animal 

Mental  states,  yes ;  we  have  names  for  dozens  of  them.  I 
know  how  I  feel  when  I  am  kicked  and  I  have  names  for  my 
feelings.  I  do  not  know  how  a  kicked  dog  feels.  I  can 
judge  only  by  his  behavior.  He  might  wag  his  tail  and  appear 
to  like  it.  I  could  then  only  understand  his  behavior  by  know- 
ing his  history:  the  kick  might  be  an  invitation  to  a  fox-hunt. 

Mind,  like  life  itself,  is  quantitative.  I  stretch  my  arms,  a 
button  pops  off  my  vest.  I  decide  to  change  my  tailor,  or 
reduce,  or  have  the  button  sewed  on  in  the  morning,  or  sew  it 
on  myself.   I  do  nothing.   Another  button  pops.   Now  what? 

The  ameba  has  no  buttons  to  worry  about.  Sound  and 
sight  of  buttons  never  enter  its  mind.  The  stimuli  which 
beat  upon  it  from  the  time  it  is  pried  or  kicked  loose  from 
another  ameba  until  it  loses  its  own  identity  by  dividing  into 
two  amebae  are  not  such  as  beat  upon  the  near-by  frog  that 
is  now  calling  its  mate. 

We  cannot  know  how  the  world  looks  to  the  ameba.  But 
we  can  put  questions  to  it:  what  do  you  think  of  red  ink — 
do  you  like  it,  can  you  digest  it,  do  you  want  more?  How 
does  it  feel  to  be  turned  loose  in  a  drop  of  water,  with  nothing 
to  stand  on  or  hang  to?  Such  questions  are  put  to  amebae  and 
to  other  living  creatures.  These  questions  are  in  terms  of 
physical  and  chemical  change  in  environment.  By  their 
behavior  under  changed  conditions  inferences  are  drawn  as 
to  their  mind. 

But  the  ameba's  mind  must  be  of  a  different  quantity  from 
ours.  We  "smell"  and  "taste"  food.  Can  it  distinguish 
brickdust  from  protoplasmic  dust  by  smell  and  taste?  It  can 
make  the  distinction — and  does,  without  visible  structure  of 
taste  or  olfactory  organs. 

By  its  behavior  we  know  that  the  ameba  distinguishes  and 
that  in  certain  ways  it  makes  finer  discriminations  than  we 
do.  Whatever  its  senses,  we  can  only  say  they  are  appro- 
priate to  its  needs. 



When  Jennings  says  that  the  ameba  "reacts  to  all  classes  of 
stimuli  to  which  higher  animals  react,"  he  simply  bears 
testimony  to  an  inherent  criterion  of  living  organisms:  a 
certain  kind  of  reaction  system.  By  that  system  they  main- 
tain a  certain  dynamic  equilibrium  and  thereby  adjust  them- 
selves to  stimuli  destructive  of  and  favorable  to  life.  If 
that  system  fails,  they  lose  their  minds — as  does  a  drop  of 
vrater  when  an  electric  current  passes  through  it. 

In  other  words,  it  is  time  to  give  the  mind  a  rest.  The 
loose  use  of  the  word  has  probably  done  more  to  befog  think- 
ing than  any  other  word,  except  possibly  "unconscious."  It 
means  so  much  it  means  nothing.  By  using  it  in  connection 
with  animal  behavior  it  implies  some  transcendental  mystery 
in  living  organisms.  There  is  much  ignorance  among  human 
beings  as  to  the  nature  of  human  beings — so  much,  in  fact, 
that  it  borders  on  the  mysterious;  but  the  mystery  of  a  sand 
dune,  of  a  snow  crystal,  of  a  flash  of  lightning,  and  of  an 
am.eba's  response  to  a  lump  of  sugar  or  a  bull's  to  a  red  rag, 
is  all  of  the  same  order.  To  identify  mind  with  protoplasm 
or  with  nervous  action  is  to  talk  about  a  hole  in  the  ether  or 
disembodied  spirits.  This  is  not  a  static  world,  and  matter 
will  cut  up  as  long  as  the  sun  shines.  When  matter  is  as 
complex  and  has  had  as  much  experience  as  has  the  stuff  of 
which  we  are  made,  it  seems  inevitable  that  it  should  have 
a  vast  capacity  to  vary  its  behavior  in  response  to  the  situa- 
tion in  which  it  finds  itself.  It  can  do  this  because  it  is  irri- 
table. When  it  can  no  longer  get  excited  about  certain  things, 
it  is  finished  as  protoplasm.  If  you  still  insist  on  mind,  call 
it  a  manifestation  of  the  kind  of  excitability  that  inheres  in 
all  dynamically  active  protein  compounds  called  living 

Meanwhile,  we  shall  do  well  to  recognize,  with  Herrick, 
that  the  real  problems  of  human  psychology  are  still  over  our 
head  and  that  the  problems  of  animal  psychology  are  pro- 
portionately difficult  as  their  sensori-motor  organization 
diff'ers  from  ours.    "The  popular  dramatization  of  animal 



life  and  imputation  to  them  of  human  thoughts  and  feelings 
may  have  a  certain  justification  for  literary  or  pedagogic 
purposes,  the  same  as  other  fairy  stories.  But  let  it  not  be 
forgotten  that  this  is  fiction  for  children,  not  science  nor  the 
foundation  of  science." 


The  microscope  reveals  no  nerves  in  the  ameba.  But  the 
ameba  has  curiosity:  it  explores  its  world,  even  though  that 
world  is  less  than  a  drop  of  water.  The  ameba  is  an  individ- 
ual, as  was  Socrates,  or  as  you  and  I  are.  Socrates  was 
condemned  to  death  for  corrupting  the  morals  of  the  youth! 
He  had  irritated  some  of  the  best  minds. 

All  life  is  irritable.  This  irritability  inheres  in  every  liv- 
ing cell  of  every  living  body.  Because  of  that  quality  the 
ameba  is  excited  to  explore  its  world  and  man  his.  That 
quality  leads  to  the  ego  in  the  individual  and  to  culture  in 
the  human  race. 

The  enemies  of  Socrates  were  so  excited  that  they  put  him 
to  death.  Hunger  can  so  excite  an  ameba  that  it  commits 
cannibalism.  Moisture  and  heat  so  excite  a  grain  of  wheat 
that  it  sprouts;  if  it  does  not  respond  to  sprouting  stimuli,  it 
is  dead.   An  ameba  beyond  the  stage  of  excitability  is  dead. 

Irritability  is  in  the  nature  of  living  things,  regardless  of 
size  and  shape,  whether  plant  or  animal,  one-celled  or  many- 
celled,  and  of  every  cell  in  every  living  body.  Because  of  this 
irritability,  life  responds.  An  ameba  responds  to  hunger 
by  pursuit  and  capture.  These  actions  are  responses,  reac- 
tions. My  response  to  fried  chicken  may  be  a  smile,  mouth 
water,  and  activity  in  the  mastication  mechanism.  My  re- 
sponse to  fried  chicken  half  an  hour  later  may  be  a  sickly 
grin;  I  do  not  want  to  think  of  food.  The  ameba  acts  the 
same  way  after  a  hearty  meal. 

Without  excitability  there  could  be  no  response  to  physical 
or  chemical  change  in  environment.    Any  change  in  the  en- 



vironment  which  causes  excitation  is  a  stimulus.  Environ- 
ment is  a  big  word  and  covers  all  outdoors  and  all  our  insides, 
including  toothache  and  an  idle  thought ;  the  kind  and  degree 
of  change  which  serves  as  stimulus  depend  on  the  organism. 
Man's  is  infinitely  complex  because  he  can  store  experience 
and  vary  or  delay  reactions  and  because  he  can  respond  with 
words  as  well  as  with  more  overt  action. 

A  baby  cries  in  the  next  room;  my  response  to  that  stimulus 
may  be  words,  or  a  bottle,  or  any  one  of  many  possible  re- 
sponses. The  response  I  make  will  depend  on  a  lifetime's 
accumulation  of  stimuli  and  reactions. 

Our  brain  itself  and  our  wonderful  special  sense  organs 
are  rooted  in  the  nature  of  living  things  to  maintain  their 
dynamic  equilibrium  by  appropriate  reactions  to  vital  stimuli. 
When  we  cannot  do  this,  we  are  dead  as  a  door  nail. 

Nails  react  to  chemical  and  physical  change,  but  their  re- 
actions are  because  of  the  elements  in  them  and  not  because 
they  are  nails.  Iron  may  enter  the  ameba's  soul;  its  reaction 
is  not  that  of  elements  to  elements,  but  as  a  complex  reaction- 
system.  With  that  it  can  respond  by  appropriate  action  to 
such  stimuli  as  would  leave  the  nail  unchanged  for  a  million 
years,  or  flee  from  an  acid  that  would  dissolve  the  nail  in  a 
few  moments.  The  nail  is  irritable;  but  there  is  no  sign  of 
organization  in  its  responses.  Nor  can  it  reproduce  itself, 
nor  perform  the  functions  of  metabolism,  nor  go  in  out  of  the 
rain.  It  cannot  adjust  itself  to  its  environment;  life  can,  be- 
cause it  has  an  adjusting  mechanism. 

Living  protoplasm  has  the  power  of  adjustment.  Our 
nervous  system  is  our  visible  mechanism  of  adjustment.  It 
is  new  in  life,  as  are  skeleton  and  intestine;  but  new  only  as 
a  new  contrivance  for  doing  something  that  has  been  done 
throughout  life.  The  automobile  is  a  new  contrivance  for 
getting  about,  but  living  organisms  got  about  before  there 
were  automobiles — or  legs,  or  wings,  or  fins;  and  adjusted 
themselves  to  their  environment  before  there  were  nerves  or 



The  microscope  shows  no  behavior  mechanism  in  an  egg- 
cell.  But  a  pin-prick  in  the  membrane  of  that  cell  causes  it 
to  vary  its  behavior:  it  dies.  That  same  pin-prick  in  another 
egg-cell  may  start  it  on  a  road  which  ends  with  a  frog.  Is 
this  "behavior"  or  "metabolism,"  psychology  or  physiology? 
Once  it  would  have  been  called  black  magic,  and  Loeb,  the 
man  who  did  it,  would  have  been  hanged — or  made  high 

To-day  the  man  who  describes  one  ameba  chasing  another 
calls  himself  a  psychologist;  the  man  who  describes  what 
happens  to  the  ameba  that  is  caught  calls  himself  a  physiolo- 
gist. Yet  chase  and  digestion  are  two  aspects  of  the  same 
problem:  why  protoplasm  and  man  go  to  war.  In  other 
words  the  fundamental  difference  between  physiology  and 
psychology  is  precisely  nil. 

In  chase  and  digestion  the  ameba  reacted,  behaved.  It 
moved:  it  has  power  of  locomotion.  Its  movements  were 
purposive.  It  persisted.  It  tried  and  tried  again.  And  does 
other  tricks  which  are  black  magic  unless  we  assume  that  the 
lowly  ameba  is  in  all  essential  respects  organized  for  life. 
It  is  the  inherent  character  of  excitability  that  comes  at  last  to 
be  expressed  in  nerves.  Nerves  are  late  in  life,  excitability 
began  with  life. 

A  flea  bites  an  elephant's  tail.  The  flea-bite  is  a  stimulus. 
The  stimulus  excites — what?  The  tail?  No;  the  elephant. 
The  elephant  is  annoyed  and  decides  to  lash  its  tail  to  shake 
the  flea  off".  The  fact  that  the  stimulus  led  to  action  implies 
more  than  mere  irritability.  The  stimulus  was  transmitted 
across  many  feet  of  elephant  body.  That  implies  a  conduction 

The  ameba  is  not  so  large.  The  space  a  stimulus  must 
traverse  across  its  body  is  measured  with  a  microscope.  But 
the  stimulus  is  conducted  across  its  body  as  it  is  the  length  of 
the  elephant's  body.  Protoplasm  is  so  organized  that  an  ex- 
citing stimulus  can  be  transmitted  throughout  its  body.  It 



responds  as  an  individual  and  thereby  adjusts  itself  to  its 

It  is  the  excitation-conduction  system  of  living  organisms 
which  makes  adjustment  possible.  That  system  began  with 
the  lowest  form  of  life,  it  is  as  old  as  life  itself.  It  grew  more 
complex  as  the  organism  became  more  complex.  It  led  finally 
to  special  organs  for  receiving  stimuli,  special  wires  for  con- 
ducting stimuli,  and  special  motor  machinery  for  reactions 
according  to  the  needs  of  the  organism  as  a  whole  for  ad- 

Excitation,  as  Child  points  out,  is  the  great  energy-liberat- 
ing process;  it  leads  to  faster  living.  In  conduction,  excita- 
tion passes  from  one  region  to  another.  The  dynamic  change 
in  the  excited  region  is  the  exciting  factor  in  the  adjoining 
region.  But  both  excitation  and  conduction  are  not  only  inde- 
pendent of  specific  forms  of  life,  but  also  of  the  nature  of 
the  stimulus  or  external  factor.  Which  means  that  the 
nervous  system  is  to  be  thought  of  in  more  than  mere  terms 
of  structure. 

In  fact,  apart  from  teeth  and  bones,  there  is  little  or  noth- 
ing in  the  human  body  that  has  meaning  as  mere  structure — 
or  as  mere  function.  Structure  and  function  are  inseparable 
in  living  organisms. 

For  more  than  3,500  years  anatomists  studied  blood  vessels 
and  blood — and  knew  next  to  nothing  or  worse  than  nothing 
about  the  marvelous  river  of  blood  which  ceaselessly  bathes 
the  myriads  of  living  cells  of  the  living  body.  Because  it 
does  bathe  these  cells,  carrying  to  them  what  every  living  cell 
must  have  (nourishment  and  oxygen)  and  relieving  them 
of  what  every  living  cell  must  be  rid  of  (refuse),  the  enor- 
mously complex  bodies  of  Man  and  animals  above  the 
humblest  are  possible.  The  blood  stream  made  integration 
possible  in  complex  bodies — such  complex  structures  could 
function  as  a  unit;  the  blood  made  for  a  degree  and  a  kind 
of  individuality  in  a  complex  organism  otherwise  impossible. 

Now  note:  the  blood  transports  chemical  substances.  But 



that  is  not  enough.  My  feet  may  be  ever  so  bountifully  sup- 
plied with  blood  and  my  transportation  system  may  be  doing 
its  work  perfectly.  But  suppose  I  have  stepped  on  a  tack  or 
want  to  tell  my  feet  to  get  a  move  on:  how  can  my  fopt 
tell  me  about  the  tack  or  how  can  I  tell  my  feet  to  move 
faster?  Here  is  where  the  nervous  system  comes  in  as  co- 
partner with  the  blood  as  an  integrating  mechanism. 

The  blood  carries  matter;  what  do  the  nerves  carry — elec- 
trons, charges  of  electricity?  Possibly.  At  any  rate,  all  liv- 
ing protoplasm  is  irritable  and  presumably  electrically  sen- 
sitive. Whatever  it  is  that  nerves  carry,  there  is  no  doubt 
as  to  results:  physiological  influences,  excitatory  or  inhibi- 
tory, are  transmitted.  With  nerves,  quick  action  at  a  distance 
is  possible ;  a  complex  mechanism  is  knit  into  one  going  con- 
cern. The  nervous  system  is  the  great  integrating  and  co- 
ordinating organ.  By  specializing  in  conduction  it  makes 
possible  quick  action  in  distant  members,  widely  scattered 
regions,  multifarious  organs,  and  diverse  tissues;  the  entire 
organism  can  thereby  adjust  as  an  individual. 

There  is  nothing  simple  about  our  nervous  system,  nor  even 
of  any  one  of  its  billions  of  component  cells,  but  as  long  as  we 
keep  in  mind  its  nature  we  can  make  progress  in  under- 
standing it — and  that  is  a  long  step  toward  understanding  pa, 
ma,  and  the  baby. 


A  ray  of  sunlight  through  a  hole  in  an  awning  strikes  me 
on  the  brow;  I  do  not  sense  it.  A  moment  later  the  same 
ray  strikes  me  in  the  eye;  now  I  sense  it.  It  is  a  decided 
stimulus.  I  respond,  become  dynamically  active.  I  move  my 
chair;  hundreds  of  muscles  are  involved  in  the  adjusting  re- 
action. Yet  if  that  had  been  a  ray  of  tropic  sun,  I  might 
have  felt  it  on  my  brow  as  heat;  and  responded  with  appro- 
priate movements.  My  response  in  one  case  was  called  out 
by  a  stimulus  to  an  organ  (my  eye) ,  in  the  other  by  a  stimulus 



to  a  region  (my  skin) ;  but  in  both  responses  my  adjustment 
was  made  with  reference  to  a  new  relation  between  myself 
and  my  environment. 

A  light  ray  falling  on  any  part  of  an  ameba's  body  is 
sensed;  the  animal  as  a  whole  makes  appropriate  response. 

There  is  a  difference.  I  was  stimulated  by  the  light  ray 
only  as  light  or  only  as  heat.  By  light  only  when  the  ray 
fell  on  an  organ  specialized  for  light:  that  is,  for  ether  vibra- 
tions of  certain  length.  The  ameba  felt  the  ray  as  vibration, 
but  whether  as  heat  or  as  light  we  do  not  know.  What  is 
certain  is  that  its  entire  outer  surface  is  sensitive  to  ether 
vibrations.  Its  whole  outer  surface,  therefore,  may  be  said 
to  be  receptive.  Through  its  "skin"  it  receives  stimuli  from 
the  outside  world.  Its  entire  exterior  surface  is  its  receptor 
of  stimuli. 

Both  ameba  and  man  responded  to  the  ether-wave  stimulus. 
This  implies  two  additional  processes.  First,  some  means  of 
communication  whereby  the  stimulus  was  transmitted  from 
exterior  (skin  or  eye)  to  the  body  within.  In  man,  the  means 
of  communication  was  a  nerve;  the  nerve  was  the  conductor. 
There  are  no  nerves  in  the  ameba ;  yet  the  message  was  trans- 
mitted. The  response  in  both  animals  was  movement — ad- 
justment. This  was  effected  in  man  by  certain  body  move- 
ments; also  in  the  ameba.  In  man,  the  movements  took 
place  through  the  mechanism  of  muscles  and  bones,  activity 
in  glands,  etc.  This  mechanism  cannot  be  discovered  in  the 
ameba,  but  by  some  means  the  body  responded;  the  message 
was  carried  out.   The  means  in  both  animals  was  the  ejfector. 

From  ameba  to  man  is  a  long  jump  in  evolution.  What 
evolved:  what  is  back  of  man's  complex  nervous  system  and 
his  many  complexes  of  behavior?  Evidently  some  sort  of 
system  as  old  as  life  itself  and  inherent  in  every  living  being. 
This  system  implies  excitability  and  transmission  in  general, 
and  in  particular,  receptor,  conductor,  effector.  Through  a 
system  of  this  pattern  man  and  every  living  being  make  ad- 
justments to  environment. 



Through  evolution  this  system  of  adjustment  has  developed 
into  certain  mechanisms  and  methods.  Man's  responses  are 
not  ameba's,  nor  elephant's,  nor  gorilla's;  the  environment 
to  which  he  must  make  adjustment  is  his  own,  his  responses 
are  his  own. 

Two  important  points  as  to  the  nature  of  the  nervous  system 
can  now  be  seen  in  bold  relief: 

First,  in  spite  of  structural  complexity  the  nervous  system 
of  man  and  higher  animals  can  be  conceived  of  in  terms 
of  conductors  of  messages  from  receptors  to  effectors.  The 
three  make  up  the  reflex  arc.  The  arc  itself  is  not  seen  as 
structure  in  low  organisms — but  they  react  as  though  the 
arc  were  present.  In  other  words,  the  reflex  arc  is  something 
new  as  visible  structure  in  evolution;  the  dynamic  action 
performed  by  the  reflex  arc  inheres  in  ameba,  hen's  egg, 
muscle  cell,  every  living  thing. 

Second,  the  receptors  in  man's  earliest  ancestors  were  on 
the  external  surface.  Where  else  should  we  expect  to  find 
them?  Life  adjusts  to  externals;  it  must  be  so  organized  that 
it  can  keep  in  touch  with  externals.  Man's  receptors  are  on 
or  in  his  skin,  or  begin  their  embryological  development,  as 
does  his  entire  nervous  system,  from  the  outer  germ-layer. 
Temperature  and  tactile  receptors  are  pure  skin  structures, 
and  as  compared  with  such  special  sense  organs  as  eye,  ear, 
and  nose,  are  in  some  respects  more  primitive  than  those  of 
any  other  warm-blooded  animal.  But  all  receptors  are  so 
located  as  to  be  exposed  to  the  action  of  environment  change. 

As  the  entire  outer  surface  of  the  ameba  is  sensitive,  so 
man's  entire  outer  germ-layer  is  potentially  nervous.  But 
the  nervous  system  itself  as  it  exists  in  man  is  simply  the 
final  product  of  the  evolution  of  the  excitability-transmission 
relation  of  living  protoplasm.  Its  complexity  in  man — 
especially  of  brain  cortex — is  a  measure  of  his  capacity  to 
escape  the  limitations  of  behavior  set  by  the  reflex  arc.  He 
can  refer  his  reactions  to  a  higher  court.    But  even  reactions 



in  this  higher  court  are  based  fundamentally  on  reflex  arc 
units.    The  reflex  arc  is  the  basis  of  all  human  behavior. 

While  the  conception  of  a  reflex  arc  in  which  response  fol- 
lows stimulus  as  does  the  ringing  of  a  bell  the  pushing  of  a 
button,  is  valuable,  it  must  be  understood  that  the  simple 
reflex  is  a  "convenient  abstraction,"  as  Herrick  calls  it.  It 
is  no  master  key  to  unlock  the  secrets  of  the  brain.  In  actual 
fact,  "each  reflex  center  is  usually  a  region  where  more  or 
less  complex  compounding  of  simple  reflexes  is  eff'ected, 
where  a  single  afferent  impulse  is  distributed  to  all  the 
muscles  necessary  for  the  complex  motor  response,  where  an- 
tagonistic impulses  meet  and  struggle  for  possession  of  a 
final  common  path,  or  some  other  correlation  of  higher  order 
is  eff'ected." 

All  this  does  not,  of  course,  diminish  the  value  of  the 
concept  of  the  arc  as  the  mechanism  for  immediate  response 
in  unit  behavior.  This  unit,  says  Herrick,  involves  the  follow- 
ing processes:  stimulus  (some  physical  agent  impinging  upon 
excitable  protoplasm) ;  excitation  (eff*ect  of  the  stimulus  upon 
some  receptive  apparatus) ;  aff'erent  transmission  to  a  center 
of  correlation;  central  adjustment  (whereby  the  aff'erent  im- 
pulse is  transferred  to  an  eff*erent  pathway) ;  eff'erent  trans- 
mission (to  some  specific  peripheral  or  end  organ  of  re- 
sponse) ;  response  (in  some  specific  eff'ector — muscle,  gland, 

The  possible  permutations  of  reflex  arcs  which  form  the 
bases  of  human  behavior  reach  staggering  figures,  unnum- 
bered billions.  Therein  rests  man's  capacity  to  learn  to  do 
new  things,  to  react  to  situations  not  predetermined  by  his 
inherited  structure. 


Living  beings  as  transformers  of  energy  give  us  the  clue 
to  the  second  great  step  in  evolution  and  an  insight  into  the 
nature  of  nerves;  and  thereby  a  better  understanding  of  the 
life  of  man. 



The  transformation  of  energy  is  a  dynamic  process.  It 
implies  motion,  movement.  Movement  implies  force,  power. 
Living  beings  are  power  plants  generating  energy  for  home 
consumption.  They  must  be,  because  living  beings  must  have 
something  to  live  on,  raw  materials  to  be  built  into  living 
bodies.  These  materials  exist  outside  the  body.  They  must 
be  captured  from  the  outer  environment  and  brought  within 
the  body  cavity.  Within,  they  are  inspected;  what  can  be 
used  is  used;  the  refuse  is  then  ejected.  These  physiological 
processes  are  purely  material  (chemical)  exchange.  Life 
trades  with  the  world  of  environment  and  in  death  balances 
the  account. 

This  material  relation  of  living  beings  to  environment  is 
only  possible  because  life  is  dynamically  related  to  environ- 
ment. Living  beings  are  so  constituted  that  environment  so 
acts  on  them  that  they  react.  The  more  complicated  the 
organism,  the  higher  the  rate  of  dynamic  action. 

This  is  beautifully  illustrated  in  the  respiration  rate  in  the 
human  brain.  The  cortex  or  gray  matter  is  the  region  of 
highest  activity;  it  consumes  twice  the  oxygen  and  liberates 
one  and  one-half  times  the  carbon  dioxide  the  white  matter 
of  the  brain  does.  Measured  by  oxygen  consumed  and  car- 
bon dioxide  produced,  the  dynamic  activity  of  the  cerebrum 
is  greater  than  that  of  the  cerebellum.  And  so  on,  down 
through  the  various  regions  of  the  brain  to  spinal  cord,  which 
has  the  lowest  rate  of  all. 

Material  exchange  in  one-celled  organisms  is  effected 
through  the  exterior  surface.  This  naturally  limits  the  size  of 
the  organism,  both  for  growth  or  material  relations  to  en- 
vironment and  for  change  or  dynamic  relations.  Hence  the 
energy  requirement  of  living  organisms  varies  according  to 
surface  area  rather  than  to  volume  of  body.  A  dog  trans- 
forms more  energy  relatively  than  an  elephant;  a  baby  needs 
more  energy  relatively  than  its  father. 

Why  "naturally"?  Because,  as  we  have  already  seen,  any 
increase  in  size  causes  volume  to  increase  faster  than  surface. 



The  combined  surface  area  of  one  billion  amebae  is  six  hun- 
dred thousand  times  greater  than  that  of  one  ameba  with  a 
volume  equal  to  that  of  the  billion  individuals.  Using  Hux- 
ley's metaphor,  our  fictitious  one-billion-amebae-sized  ameba 
has  increased  its  population  (volume)  six  hundred  thousand 
times  faster  than  it  has  increased  its  import  and  export 
facilities  (surface  area). 

Life  cannot  do  business  under  such  conditions.  In  the 
course  of  evolution  the  processes  we  call  "living"  began 
to  occur  in  exceedingly  small  bits  of  protoplasm ;  these  small 
bits  (cells,  protozoa,  etc.)  have  remained  the  physico-chemical 
units  of  all  living  processes  and  of  all  living  beings. 

The  second  great  step  in  organic  evolution  occurred  when 
these  units  were  impelled  by  certain  natural  forces  to  pool 
their  interests  and  thus  form  larger  and  larger  co-operative 

Now  for  the  behavior,  or  dynamic  relation,  of  the  organism 
as  a  transformer  of  energy.  A  raindrop  on  my  hand  may  be 
as  effective  a  stimulus  as  a  cloudburst  to  drive  me  to  cover. 
But  a  slight  stimulus  is  effective  only  over  part  of  an  ameba. 
The  stimulus  may  be  so  slight  that  it  "dies  out"  before  it  is 
transmitted  across  the  ameba's  body.  There  is  no  special 
conducting  path  in  the  ameba. 

I  may  shout  and  shout  in  my  room :  no  one  in  the  office  be- 
low hears  me,  although  the  man  in  the  next  room  may  be 
annoyed  and  the  man  in  the  room  beyond  excited.  My  voice, 
through  a  speaking  tube  or  telephone  wire,  is  conducted  to 
the  office  below,  or  halfway  round  the  world. 

For  stimulus  to  carry  across  the  body  of  an  ameba,  it  must 
be  of  a  certain  intensity.  The  greater  the  distance  across  its 
body,  the  more  intense  must  be  the  stimulus  to  traverse  that 
distance.  In  other  words,  without  definite  paths  of  conduc- 
tion it  must  be  assumed  that  in  low  organisms  every  stimulus 
is  conducted  with  a  loss  or  decrement  and  that  stimuli  of  vary- 
ing quantity  provoke  reactions  of  varying  quantity. 

Nerves,  then,  are  primarily  conductors,  paths  along  which 



impulses  are  transmitted.  They  do  it  at  a  speed  of  about 
400  feet  a  second.  The  nature  of  the  impulse  they  conduct 
is  not  known.  Nerves  can  be  artificially  stimulated  by 
mechanical,  thermal,  chemical,  and  electrical  means.  The 
impulse  itself  must  be  some  form  of  energy.  The  conduction 
is  probably  electrical  in  nature,  but  presumably  not  like  that 
of  an  electric  current. 

Nerve  fiber  in  man  and  highly  organized  animals  conducts 
impulses  on  the  all-or-none  principle.  A  fly  lands  on  an 
elephant's  tail.  That  landing  is  not  an  adequate  stimulus; 
it  does  not  pass  the  threshold.  But  if  the  fly  bites  the  tail, 
the  stimulus  is  adequate;  it  passes  the  lowest  limit  (threshold) 
which  will  bring  about  a  reaction.  The  impulse,  being  suf- 
ficient to  pass  the  threshold,  is  delivered  as  a  maximal  excita- 
tion and  without  decrement,  regardless  of  the  strength  or  in- 
tensity of  the  stimulus. 

We  may,  then,  think  of  life  as  having  moved  from  a  one- 
cell  hive  into  a  mansion  of  countless  cells  because  the  outside 
world  of  environment  excited  life  to  wider  activity.  It  could 
make  the  move  only  through  specialization  in  the  excitation- 
response  mechanism.  With  man,  that  mechanism  reached 
such  perfection  with  all-or-none  conduction  and  all-or-none 
muscle  engines  that  one  pistol  shot  could  fire  all  civilization, 
as  one  small  spark  can  fire  a  whole  magazine  of  powder. 


Reflex  action  requires  no  reflection;  if  it  did,  we  should 
have  no  time  to  reflect.  Yet  they  are  from  the  same  word, 
"to  bend  back."  In  reflection,  we  turn  the  memory  pages  of 
a  misspent  career  or  whatever  it  is  we  are  reflecting  about. 
In  reflexes,  life  itself  knows  how  to  act;  we  may  or  may  not 
be  conscious  of  the  act. 

I  am  writing.  From  time  to  time  my  eyelids  snap  shut; 
I  am  not  conscious  of  it,  nor  is  the  blinking  due  to  conscious 
eff'ort.    My  eyes  blink  as  fast  as  dust  or  dryness  stimulates 



certain  nerves  to  close  the  lids.  The  stimulus  removed,  other 
muscles  open  the  lids. 

If  the  stimulus  is  a  cinder,  mere  winking  might  not  remove 
it;  the  lids  may  be  drawn  tighter.  Meanwhile  I  become  con- 
scious: pain  has  come  as  a  stimulus.  I  react  now.  But  my 
effort  to  overcome  reflex  effort  may  not  suffice:  I  may  have  to 
use  strong  finger  muscles  to  overcome  the  pull  of  less  strong 
eyelid  muscles. 

The  eye-blink  was  a  reflex  action.  It  started  with  excitation 
in  my  eye  due  to  an  external  stimulus.  That  excitation  was 
conducted  by  a  nerve  to  the  central  nervous  system;  from 
central  by  another  nerve  to  eyelid  muscles:  they  contracted. 
The  structure  or  mechanism  involved — receptor  (eye),  con- 
ductor (nerve),  effector  (muscle) — is  a  reflex  arc;  the  action 
involved  in  a  reflex  act.  On  the  other  hand,  my  behavior  in 
removing  the  cinder — perhaps  involving  a  mirror,  cotton, 
match,  or  a  journey  to  a  physician — was  a  general  reaction 
and  far  from  simple. 

The  arc  in  the  eye-blink  functioned  as  a  unit;  the  reflex 
act  performed  a  definite  service  of  biologic  value.  And  work 
of  arc  and  result  of  act  both  transpire  without  my  knowing 
or  heeding.  Only  when  the  arc  fails  to  work,  or  when  the 
act  fails  to  remove  the  cause  of  excitation,  does  consciousness 
take  charge. 

The  reflex  arc,  then,  is  an  instinctive  mechanism  to  trans- 
late impulse  into  action.  It  is  the  simplest  unit  of  reaction; 
the  reflex  act  the  simplest  adapted  or  purposive  unit-response 
to  an  external  excitation.  Arc  and  act  made  higher  organisms 
possible.  Through  them  order  and  unity  are  preserved  in 
highly  complex  forms.  With  the  appearance  of  brain  and 
spinal  cord  as  central  adjustor  for  these  many  arcs,  the  evolu- 
tion of  monkeys  and  man  was  well  on  the  way. 

Why  does  the  eye  blink — at  a  shadow  even?  Why  does  an 
invisible  speck  of  dust  close  the  eye?  Or  a  speck  of  pepper 
set  the  lachrymal  glands  to  secreting?  Or  a  sudden  strange 
noise  touch  off  the  whole  body,  including  rate  of  heartbeat, 



change  in  composition  of  the  blood,  activity  in  a  thousand 

What  happens,  how  the  excitation  is  conducted  to  the 
eflPector  muscle  of  eyelid,  lachrymal  gland,  etc.,  is  generally 
fairly  clear.  How  the  stimulus  excites  is  still  a  profound 
secret.    How  does  the  message  get  on  the  wire? 

At  any  rate,  it  does.  And  it  is  also  in  the  nature  of  the 
wires  to  central  that  messages  marked:  "Answer  urgent"  are 
given  precedence.  Herein  is  the  biologic  value  of  the  reflexes. 
The  newborn  babe  does  not  have  to  think  about  food,  much 
less  have  to  learn  to  close  its  windpipe  when  swallowing:  it 
does  not  even  have  to  learn  to  suck — and  that  is  a  very  com- 
plex process. 

Reflexes  are  inherited  types  of  action;  they  go  with  the 
birthright.  Some  function  before  the  doctor  can  say,  "It's  a 
boy!";  some  appear  only  after  some  hours;  some,  only  after 
weeks.  The  grasping  reflex  is  so  well  developed  at  birth  that 
a  normal  child  can  support  its  body  by  grasping  a  broom 
handle.  In  a  baby  born  without  a  brain  this  reflex  persisted 
till  its  death  at  the  eighteenth  day.  The  babe  can  close  its 
eyes  from  birth.  The  blink-reflex  appears  in  the  third  month. 
It  can  shed  tears  in  the  fourth  month. 

Some  reflexes  are  simple,  such  as  the  eye-blink;  some, 
complex — many  muscles  or  glands  respond,  as  in  tickling; 
some  spread — diff'erent  parts  of  or  the  whole  body  responds; 
some,  periodic — the  reaction  is  repeated,  trembling,  coughing, 
hiccoughing,  sneezing,  swallowing. 

WTien  we  are  keyed  up  our  reflexes  are  quick  and  intense — 
tonic.  A  "nervous"  person  jumps  at  anything.  A  brainless 
frog  injected  with  a  strychnine  solution  is  very  sensitive  to 
reflex  stimuli:  the  slamming  of  a  door  sets  it  jumping!  Mental 
eff'ort  to  inhibit  pain  intensifies  the  agony  of  human  beings 
suff'ering  cramps  caused  by  strychnine  or  tetanus  poisoning. 
It  is  like  trying  to  go  to  sleep:  the  harder  we  try,  the  wider 
awake  we  are. 

Reflex  action  may  be  conditioned  and  habits  of  reaction 



developed  to  work  like  reflexes;  otherwise  our  newborns  would 
have  a  hard  row  to  hoe.  If  we  had  to  depend  on  our  inherited 
reflexes  and  instinctive  types  of  behavior,  we  should  never 
be  as  clever  as  the  bees  and  ants  nor  have  as  much  intelligence 
as  a  capuchin  monkey. 

Man's  inherited  reflex  action  repertoire  is  just  enough  to 
keep  him  on  the  floor.  A  chick  and  a  colt  inherit  a  better 
set  than  that.  Ours  are  of  enormous  importance  and  save 
us  time,  eflfort,  energy.  But  what  counts  most  in  human  be- 
havior is  the  manner  in  which  they  are  "conditioned"  and 
what  kind  of  habits  are  built  upon  and  around  them.  They 
arose  in  response  to  certain  organic  needs ;  too  often  they  are 
conditioned  in  ignorance,  superstition,  selfishness,  or  vice; 
or  in  the  lap  of  luxury  as  sources  of  amusement  and  family 
pride — equally  useless  for  society. 


Living  protoplasm  is  excitable;  with  nerves,  it  is  more 
easily  excitable;  with  brains,  it  need  not  get  excited  and  so 
can  find  time  to  go  a-fishing.  The  nature  of  nerves,  then,  is 
to  make  us  nervous.  Therein  is  the  real  diff'erence  between 
man  and  tree:  with  nerves,  the  tree  would  be  the  higher  life. 

The  baby  is  a  "bundle  of  nerves" — and  gets  on  mother's. 
And  grows  along  at  the  usual  rate,  knowing  nothing  of  nerves. 
Then,  without  a  second's  warning,  comes  a  day  when  the 
youngster  cries  out,  "Got  the  toothache!" 

That  means  that  the  nerve  back  of  that  "toothache"  is 
exposed  to  the  world.  That  is  why  it  cries  out:  exposure  to 
the  world  is  not  the  way  nerves  were  brought  up.  Nerves 
are  not  accustomed  to  exposure,  nor  adapted  to  contact  with 
outdoor  environment.  They  are  inside  performers:  they 
carry  messages  from  somewhere  within  the  body  to  something 
within  the  body.  The  "somewhere"  may  be  a  cell  or  group 
of  cells  on  or  anywhere  within  the  body,  but  normally  not  in 
the  nerve  itself. 



No  tooth  "aches."  When  certain  cells  became  enamel, 
otliers  dentine,  and  others  cementum,  and  united  to  build  a 
tooth,  they  traded  feeling  for  form  and  surrendered  most  of 
their  excitable  heritage  to  become  almost  solid  ivory.  That 
is  why  the  nerve  inside  the  tooth  gets  so  sore  when  the  tooth 
gives  it  the  air,  so  to  speak. 

It  is  the  nature  of  nerves  to  be  extraordinarily  sensitive  to 
and  remarkably  efficient  conductors  of  excitation.  Hence  the 
whole  mechanism  of  end-receptors:  shock  absorbers;  they 
break  the  news  to  the  nerves,  gently  but  firmly.  It  is  the 
nerves'  business  to  send  the  news  to  the  proper  organ  for 
response.  If  the  news  is  startling  or  in  code,  it  will  be  carried 
to  the  higher  brain  center  for  consideration  or  decoding. 

I  go  along  a  dusty  pike  in  my  bare  feet.  I  cut  my  foot  on 
a  bit  of  glass.  It  does  not  hurt  much;  and  if  I  am  on  my 
way  to  the  swimming  hole,  I  do  not  mind  it.  Who  told  me  my 
foot  was  cut,  or  that  it  was  not  a  tack  I  had  stepped  on?  Per- 
haps a  mile  of  nerve  fibre  and  millions  of  nerve  cells  were 
involved  in  carrying  messages  before  I  finished  with  that 

We  have  big  nerves  and  little  nerves,  long  ones  and  short 
ones,  as  we  have  muscles  of  varying  length  and  size.  The 
units  are  cells:  in  muscles,  bound  into  sheaves;  in  nerves, 
bound  into  cables — trunk  lines  of  communication.  There 
the  general  resemblance  ends.  Nerve  cells  are  called  neurons 
— and  when  inflamed  spell  neuritis.  But  they  are  true  cells; 
they  have  a  nucleus  in  a  mass  of  cytoplasm  and  grow  and 
in  general  behave  like  ordinary  cells.  But  they  are  unique 
in  their  astounding  capacity  to  vary:  in  size  and  shape, 
especially  in  their  outgrowths — "infinitely  complicated  and 
bewilderingly  complex,"  Child  calls  them.  Some  are  as 
complex  in  architecture  as  elm  trees,  and  are  called  dendrons; 
also  called  afferent  because  they  carry  messages  toward 

Other  outgrowths  of  neurons  are  called  axons  (axis) ;  their 
branches  are  fewer  and  shorter;  they  are  more  slender  and 



more  uniform  than  dendrons,  and  may  be  three  feet  or  more 
in  length.  For  example,  connection  between  the  cortex  of  the 
brain  and  muscle  in  the  calf  of  the  leg  may  be  made  by  two 
neurons:  an  upper  motor  neuron  which  extends  to  the  lower 
end  of  the  spinal  cord,  a  lower  or  peripheral  motor  neuron 
of  the  sciatic  nerve  which  ends  in  a  muscle  of  the  calf.  Axons 
are  also  called  efferent:  they  carry  messages  from  central  to 
glands,  muscles,  etc.  Generally  a  neuron  has  only  one  axon ; 
it  may  have  several  dendrons. 

A  telephone  wire  can  transmit  messages  either  way.  Liv- 
ing protoplasm  was  organized  on  that  plan.  But  with  neuron 
conduction  paths  impulses  are  carried  only  one  way.  The 
axon  appeared  first;  it  is  more  highly  polarized  than  the  den- 
dron,  grows  faster,  is  more  sensitive.  The  dendron  is  more 
primitive,  and  perhaps  plays  a  part  in  the  nutrition  processes 
of  the  parent  neuron  and  hence  is  a  less  efficient  conductor 
of  messages. 

Each  neuron  is  a  distinct  entity  and  is  visibly  connected 
with  no  other  neuron.  The  branches  of  an  axon  generally 
interlace  into  the  branches  of  a  dendron  of  another  neuron. 
But  between  is  a  gap:  the  famous  synapse  (tying-together), 
the  junction  between  two  neurons. 

The  synapse  is  something  of  a  puzzler,  but  of  great  im- 
portance. If  it  were  perfectly  understood  we  should  have  a 
much  clearer  idea  than  we  have  now  of  many  perplexing 
problems  in  human  behavior. 

Nerve  fibre — and  muscle  cells — conduct  impulses  without 
decrement,  on  the  all-or-none  law.  At  the  synapse  the  im- 
pulse is  slowed  up  or  even  blocked ;  or  it  may  be  speeded  up. 
In  any  event,  something  happens.  Slight  resistance  is  appar- 
ently lessened  by  repeated  excitation — ^hence  the  ease  of 
action  in  habit  formations.  As  though  a  path  were  worn 
smooth  with  frequent  usage.   Why?  What  is  the  synapse? 

There  is  no  synapse  in  the  nervous  system  of  a  jellyfish, 
nor  true  neurons;  simply  a  nerve  net,  Harvey  cut  a  dough- 
nut-shaped ring  from  the  disk  of  a  jellyfish,  entrapping  a 



nerve  impulse.  That  impulse  traveled  around  that  ring  for 
eleven  days;  457  miles!  No  decrement,  no  slov/ing  up  of 
impulse.  Apparently  it  might  be  traveling  yet  had  not  the 
muscle  become  fatigued  and  had  not  the  impulse  been  inter- 
fered with  by  regenerating  tissue.  Further,  in  that  nerve  net 
impulses  travel  either  way. 

In  higher  animals,  a  synaptic  system  with  highly  special- 
ized neurons  having  numerous  and  intricate  endings  has  re- 
placed the  nerve  net.  It  is  a  more  efficient  system  in  that 
it  is  more  modifiable.  It  provides  "an  anatomical  mechanism 
for  correlation  and  co-ordinations  of  the  most  intricate  pat- 
terns, and  for  the  modification  of  the  directions  taken  by 
nervous  impulses  arising  from  transient  fluctuations  in  the 
relative  permeability  of  the  different  junctions"  (Herrick). 

The  synapse,  then,  is  a  barrier,  presumably  a  living  semi- 
pervious  membrane  through  which  ions,  bearers  of  impulses^ 
can  pass  and  in  one  direction  only;  the  physico-chemical 
nature  of  the  ions  or  conducting  substance  may  be  thereby 

Synapses  have  been  compared  to  the  valves  in  the  veins 
which  prevent  the  blood  from  flowing  backward,  but  the  com- 
parison suggests  nothing  of  the  role  played  by  the  synapse 
as  a  modifiable  tissue  making  for  impressionable  and  plastic 

With  the  arrangement  of  neurons  and  their  processes  as 
found  in  higher  animals,  the  complicated  patterns  of  sense 
organs,  nerves,  correlation  centers,  and  response  organs  of 
reflex  and  instinctive  behavior  were  passible.  With  the 
plasticity  of  the  synaptic  tissue,  the  kinds  of  memory  and 
association  which  make  for  intelligent  behavior  were  possible. 

When  that  "tooth"  begins  to  "ache"  the  nerve  that  carries 
the  ache  impulse  to  central  is  not  to  be  hushed  up  on  a  stop- 
ache  order  from  central.  It  is  central's  business  to  have  a 
look  at  that  tooth.  As  it  is  the  nature  of  nerves  to  be  nervous, 
it  is  the  business  of  brains  to  attend  to  nerves— and  to  see 



to  it  that  they  are  not  exposed  to  stimuli  for  which  they  are 
not  adapted. 

Any  one  nerve  carries  impulses  toward  or  away  from  a 
nerve  center,  not  both  ways;  it  is  either  alferent  or  efferent. 
And  when  it  is  overloaded  or  stimulated  above  normal  in- 
tensity, it  carries  a  message  of  pain  in  addition.  Therein  lies 
the  biologic  function  of  pain. 


The  world  into  which  we  are  born  is  not  a  world  of  walls, 
pictures,  floor,  rugs,  chairs,  bed,  or  even  of  bath,  mother,  and 
milk.  It  is  a  world  of  matter  and  energy,  of  things  hot  or 
cold,  soft  or  hard,  sharp  or  round,  sweet  or  sour,  of  various 
physical  and  chemical  stimuli,  of  various  kinds  of  physical 
energy,  vibrations  in  the  ether  and  in  material  media. 

The  world  into  which  we  are  born  is  a  small  world,  but  it 
is  a  world  of  stimuli. 

Some  made  us  afraid,  some  made  us  angry,  some  made  us 
smile.  What  happened  when  the  nurse  declared,  "It's  the 
homeliest  brat  I  ever  saw"?  Much,  if  the  mother  heard  it; 
to  us,  just  born,  nothing.  The  remark  was  a  stimulus,  but 
created  no  sensation  in  us:  it  was  not  an  adequate  stimulus. 
If  the  nurse  had  bawled  that  remark  in  our  ear,  we  should 
have  heard  it — for  we  were  born  with  ears  attuned  to  the 
human  voice.  And  it  would  have  frightened  us,  not  because 
of  its  sentiment,  but  because  of  its  noise.  A  loud  noise  would 
have  been  a  real  stimulus:  sound-waves  of  such  length  as  to 
disturb  our  inherited  equilibrium.  We  reacted  to  such  rude 
noises.    They  were  adequate  stimuli. 

The  world  of  our  environment  keeps  beating  in  upon  us  as 
stimuli:  pressures,  chemical  substances,  sound-waves,  light- 
waves. How  we  interpret  these  stimuli,  what  they  mean  to  us, 
these  make  up  our  world.  To  no  two  human  beings  can  the 
world  seem  the  same;  nor  be  the  same  on  any  given  two 
days  or  moments  to  the  same  individual.    Under  different 



circumstances,  the  Count  of  Monte  Cristo  would  have  traded 
his  cave  for  a  gallon  of  gasoline. 

Orion's  light-waves  have  been  stimuli  for  men's  eyes  for 
ages.  To  one  age  Orion  was  just  "stars,"  to  another  age  these 
same  light-waves  are  a  library  of  astronomy,  physics,  and 
chemistry.  A  hickory  tree  is  a  dozen  different  things  to  a 
dozen  different  men;  a  dozen  years  later  each  man  has  a 
different  notion  of  the  tree.    Same  tree. 

A  bloodhound  picks  up  a  scent  and  is  off  like  a  shot  and 
tracks  his  man  across  fields  and  through  forest.  The  stimulus 
that  hound  picked  up  means  nothing  to  man.  He  may  root 
his  nose  all  over  the  lot,  but  he  can  never  smell  the  truffles 
the  hog's  nose  finds  beneath  the  soil. 

This  outside  world  of  stimulus,  then,  is  real  to  us  only  in 
so  far  as  stimuli  reach  us  and  as  we  interpret  the  stimuli.  To 
other  animals  there  are  other  worlds  than  ours.  It  must  be 
so.  Two  men  in  an  airplane  see  two  worlds:  how  must  the 
world  they  see  look  to  an  eagle,  a  lark,  a  bat,  a  butterfly? 
The  world  is  so  different  to  some  animals  that  their  behavior 
can  be  explained  in  no  terms  of  known  sense  of  seeing,  hear- 
ing, smelling,  or  tasting. 

Man's  tongue  cannot  distinguish  sodium,  ammonium, 
lithium,  and  potassium  chlorides — they  all  taste  salt;  but  the 
earthworm  can,  and  reacts  differently  to  each. 

Cut  an  earthworm  in  two.  The  tail  end  squirms  as  though 
in  great  pain.  Not  a  squirm  from  the  other  end;  it  crawls 
away  as  unconcerned  as  you  please.  Knife  is  one  kind  of 
stimulus  to  head  end,  something  else  to  the  other  end. 

A  marked  male  m.oth  was  set  free  a  mile  and  a  half  from 
a  caged  female.  The  male  was  on  the  cage  the  next  morning. 
Our  smell  stimuli  come  in  the  form  of  gas  or  vapor.  Some 
animals  seem  to  smell  vibrations.  Ants  especially  sense 
stimuli  far  beyond  human  reach. 

The  white  rat  can  hear  a  noise,  but  not  a  tone;  a  tunins 
fork  is  no  stimulus  to  its  ear.  Sound-waves  are  stimuli  to 
such  as  are  tuned  in. 



A  shadow  is  an  adequate  stimulus  to  a  starfish.  Cut  out  its 
eyespots,  the  shadow  is  still  an  adequate  stimulus.  Other 
marine  forms  without  eyes  respond  to  shadows.  "Sensibility 
to  difference,"  Loeb  called  it.  Even  the  ameba  senses  changes 
in  intensity  of  light.  Blinded  frogs  can  distinguish  red 
from  blue  light  through  their  skin.  Yet  Watson  found  that 
rabbits  and  rats  cannot  distinguish  red  from  darkness. 

Possibly  all  animals  below  man  are  color-blind.  When  the 
bull  sees  red,  he  sees  heat.  Radiant  heat  and  light,  after  all, 
only  differ  in  wave-length;  both  are  ether  vibrations.  Certain 
animals  evidently  sense  certain  vibrations  in  their  skin  which 
are  not  stimuli  to  the  skin  of  higher  animals.  Bees  are  color- 
blind, but  they  can  see  ultra-violet  light  rays  invisible  to 
human  eyes. 

Space  relations  come  to  us  as  certain  light- wave  stimuli  and 
we  use  our  stereoscopic  vision  to  determine  these  relations. 
Yet  animals  without  stereoscopic  vision  and  with  practically 
immobile  eyes  give  evidence  of  infallible  judgment  in  esti- 
mating distance. 

How  do  they  do  it?  We  know  our  world  as  it  reaches  us, 
as  sensation.  We  know  what  our  sense  organs  sense;  the 
range  of  vibration  that  is  stimulus  for  eye  and  for  ear;  the 
range  of  chemical  change  that  serves  as  stimulus  to  tongue, 
etc.  We  know  our  environment  in  so  far  as  it  serves  as 
stimulus.  Each  kind  of  animal  and  plant  knows  its  world  in 
the  same  manner.  And  for  each  of  us  the  world  is  what  we 
sense  it.  For  many  there  are  no  rainbows,  sunsets,  or  Orions, 
except  in  picture  books. 

Think  again  of  the  child  at  birth.  To  how  few  things  is 
it  receptive!  In  almost  literal  truth,  it  has  no  "sense"  at 
all.  And  yet  a  normal  newborn  has  all  the  sense  organs  or 
receptors  of  sensations  it  will  ever  have.  They  are  the  an- 
alyzers of  stimuli  from  the  world  outside  the  body;  the 
windows  of  the  mind,  Herrick  calls  them.  Each  can  be  pene- 
trated by  or  is  receptive  to  only  certain  kinds  and  ranges  of 
external  energies.    External  ear,  refracting  media  of  the 



eye,  etc.,  are  merely  devices  which  modify,  strengthen,  or 
concentrate,  and  so  make  more  effective  the  action  of  the 
stimulus.  Rarely  is  it  the  fault  of  the  sense  organs  them- 
selves if  "having  eyes  they  see  not,  having  ears  they  hear 
not" ;  nor  if,  with  the  whole  world  as  stimulus,  they  never  get 
beyond  the  vegetable  plane  of  existence. 


Nerves  conduct  impulses.  An  impulse  is  a  push.  What 
is  it  that  pushes?  Pushes  what? 

I  look  up:  I  see  stars.  I  get  a  crack  over  the  head:  I 
see  "stars."  Same  stars?  With  an  eye  open  I  see  light.  I 
close  both  eyes  and  press  my  thumb  on  one  eye:  I  see  light. 
Remove  both  eyes  and  stimulate  either  optic  nerve  with 
electricity:  I  see  light.  Those  who  have  had  an  eye  removed 
on  the  operating  table  report  "blinding  light." 

What  do  we  see  with,  then?  Obviously,  not  with  the  eyes. 
Even  mechanical  pressure  on  the  optic  nerve,  when  the  eyes 
are  removed,  produces  a  sensation  of  light.  We  do  not 
"see"  with  that  nerve;  it  merely  conducts  the  stimulus,  the 
impulse — no  matter  who  or  what  pushed.  It  must  be  that  we 
see  with  the  brain.  We  do:  we  also  "hear"  with  the  brain. 
And  if  our  optic  nerve  were  attached  to  our  ear,  stimulus  of 
ear  would  be  received  by  the  brain  as  light. 

It  follows  that  the  impulse  which  is  carried  by  the  optic 
nerve  may  start  outside  or  on  any  part  of  the  nerve  itself, 
but  once  on  the  nerve  the  impulse  is  carried  to  the  brain  and 
there  registers  as  light,  the  intensity  depending  on  the  inten- 
sity of  the  impulse  or  stimulus.  We  say  the  light  is  seen  by 
the  eye  because  the  brain  projects  the  sensation  to  its  point 
of  origin.  Pain  in  the  stump  of  a  leg  is  often  "felt"  in  a 
foot  that  has  been  amputated. 

There  may  have  been  neither  stars  nor  light  in  sight  when 
I  received  the  crack  on  the  head ;  the  sight  center  in  the  brain 
was  stimulated:  I  saw  "stars."  The  optic  nerve  never  carries 



sound  impulses.  No  matter  what  the  impulse  that  is  put  on 
it,  the  brain  "sees"  the  impulse  as  light. 

The  eye  is  the  outer  end-organ  of  the  optic  nerve.  The 
retina  is  the  receptive  part;  it  is  part  of  the  brain  itself — the 
seeing  brain.  The  eye  is  the  most  highly  specialized  of  all 
sense  organs.  It  is  called  a  special  sense  organ  because 
specialized  to  receive  certain  stimuli  which,  carried  to  the 
brain,  arouse  a  special  sense,  the  sensation  of  sight. 

Table  of  Ether  Wave  Vibrations  ^ 

Wave  lengin 

Number  of  vibrations 
per  second 



00  to  .1  mm. 

(electric  waves) 

0  to  3,000  billion 



.1  mm.  to 
.0004  mm. 

3,000  billion  to 
800,000  billion 



.0008  mm.  to 
.0004  mm. 

400,000  billion  to 
800,000  billion 


Light  and 

.0004  mm.  to 
.000059  mm. 

800,000  billion  to 
5,100,000  billion 



.0000008  mm.  to 
.00000005  mm. 

400,000,000  billion  to 
6,000,000,000  billion 



*From  Neurology,  by  C.  Judson  Herrick,  1922,  by  permission  of  the  author 
and  the  publishers,  W.  B.  Saunders  Company. 

The  eye  itself  is  the  receiving  apparatus  for  certain  kinds 
of  physical  energy — ether-waves;  but  it  can  receive  ether- 
waves  of  certain  lengths  only.  Thus,  by  reference  to  the 
foregoing  table,  it  will  be  seen  that  of  all  the  countless  ether- 
waves  that  impinge  upon  our  retina  our  eyes  respond  only 



to  those  with  a  rate  of  vibration  of  from  400,000,000,000,000 
to  800,000,000,000,000  per  second,  one  octave  of  the  ten 
contained  in  the  solar  spectrum.  These  light-waves  travel  at 
a  velocity  of  186,000  miles  a  second  and  vary  from  1/30,000 
to  1/60,000  of  an  inch  in  length.  Within  this  range  the 
human  eye  can  distinguish  up  to  230  pure  spectral  tints  and 
up  to  600,000  degrees  of  purity  and  intensity. 

Ether-waves  vibrating  faster  than  800,000,000,000,000 
per  second  are  called  ultra-violet  rays  and  are  beyond  human 
vision.  X-rays  are  the  ether-waves  shorter  than  the  ultra- 
violet. They  are  less  than  a  quarter  of  a  millionth  of  an 
inch  long  and  vibrate  at  a  rate  from  400,000,000,000,000,- 
000  to  6,000,000,000,000,000,000  per  second.  Their  pene- 
trating power  is  also  astounding;  neither  flesh  nor  bone  stops 
them,  nor  thin  sheets  of  zinc,  iron,  or  lead.  The  existence  of 
the  three  octaves  of  the  ultra-violet  series  and  the  X-rays 
series  would  have  remained  unknown  to  man  had  they  not 
been  discovered  by  indirect  means  in  physical  laboratories. 

Above  the  octave  visible  to  the  human  eye  are  the  six 
octaves  of  the  infra-red.  Of  this  series  the  human  skin  is  re- 
ceptive to  waves  of  from  3,000,000,000,000  to  400,000,- 
000,000,000  as  radiant  heat;  as  it  is  also  to  the  octave  which 
stimulates  the  eye  as  light.  Thus,  ether-waves  of  the  same 
energy  may  be  received  by  the  eye  as  light,  by  the  skin  as 
heat.  The  physical  stimulus  is  identical;  and  presumably 
the  nerve  impulses  from  skin  and  eye  to  brain  are  identical. 
The  discrimination  is  made  in  the  brain.  Optic  nerve  im- 
pulses register  light;  warm-spot  impulses  register  heat. 

Beyond  the  infra-red  octaves  of  the  solar  spectrum  are  the 
long,  slow  electric,  or  Hertzian,  waves;  they  never  stimulate 
the  eye,  only  the  ear  when  transformed  by  a  Marconi  into 
waves  in  material  media.  Hertz's  discovery  made  the  radio 

So  also  the  human  ear  has  its  limitations  as  receptor  for 
sound-waves  or  vibrations  in  material  media.  The  normal 
ear  is  a  special  sense  organ  for  vibrations  of  about  ten  oc- 



taves,  from  forty  feet  to  one-half  inch  in  length,  and  from  30 
to  30,000  per  second.  Within  this  range  about  11,000  dif- 
ferent pitches  can  be  discriminated.  Exceptional  individuals 
are  sensitive  to  vibrations  as  slow  as  12,  as  fast  as  50,000, 
per  second.  Vibrations  ranging  from  mere  contact  up  to 
1,552  per  second  are  received  by  the  skin  and  sensed  as  touch 
or  pressure.  Compared  to  light-waves,  sound-waves  travel 
at  a  snail's  pace,  only  1,100  feet  a  second. 

The  anatomy  of  the  internal  ear  is  quite  as  complicated 
as  is  that  of  the  eye,  though  not  so  well  understood.  But 
presumably  an  essential  part  of  the  hearing  organ  is  a  tiny 
membrane  in  the  inner  ear  which  contains  about  20,000 
exceedingly  minute  short  fibres  of  varying  length.  These,  it 
is  thought,  vibrate  in  response  to  wave-lengths  transmitted 
within  through  the  ear  drum  and  the  complicated  mechanism 
of  the  middle  ear. 

Just  as  pressure  on  the  eyes  may  be  transmitted  as  light,  so 
disturbance  within  the  auditory  apparatus  registers  on  the 
auditory  nerve  as  sound.  Disturbed  blood  pressure  inside  the 
ears  gives  rise  to  such  noises  as  ringing,  roaring,  rushing,  etc. 

Both  eyes  and  ears  are  specialized  as  to  kind  and  amount  of 
stimulus  they  receive;  they  have  selective  excitability  and  so 
lower  the  threshold  of  excitability  for  specific  stimuli  and 
heighten  it  for  all  other  stimuli.  The  sound  of  a  ticking 
watch  can  be  carried  through  teeth  and  bones  to  the  auditory 
nerve;  but  the  ear  will  carry  a  tick  so  faint  that  it  will  not 
reach  that  nerve  through  teeth  and  bone. 

Our  eyes  see  more  and  our  ears  hear  more  than  a  gorilla's 
not  because  ours  are  better  receptors  or  are  excited  by  diff'er- 
ent  stimuli,  but  because  our  experience  diff'ers  from  the 
gorilla's;  the  difference  is  in  the  mind's  eye  and  ear. 

We  do  see  with  the  eyes  and  hear  with  the  ears ;  such  is  the 
nature  of  these  receptors.  Only  it  must  be  understood  that 
the  eye  is  a  photo-receptor,  the  ear  a  sound  and  position 
receptor;  our  sensations  of  sight  and  of  sound  are  dependent 
on  brain  cortex,  where  they  rise  to  consciousness.   In  dreams 



we  see  sights  and  hear  sounds — in  the  brain  cortex  only;  the 
receptors  or  end- organs  of  sights  and  sounds  may  have  re- 
ceived no  stimuli. 

When  an  end-organ  is  discovered  in  man's  body  adapted 
for  stimuli  such  as  can  be  transmitted  by  a  nerve  and  which 
can  be  produced  by  "conscious  thought"  in  another's  brain, 
then — and  not  until  then — will  it  be  time  to  investigate 
thought  transference  and  mental  telepathy.  "Spirits"  may 
communicate  with  "spirits" ;  but  allowing  myself  a  maximum 
of  "psychic"  power — ^whatever  that  means — I  can  conceive 
of  no  voice  without  mechanism,  nor  noise  without  friction. 
Science  may  never  see  with  its  eye  the  hydrogen-ion  involved 
in  nerve  conduction,  nor  know  how  atoms  or  ether  waves 
excite  living  protoplasm,  but  it  cannot  get  excited  about 
something  it  cannot  even  conceive.  When  Sir  Oliver  Lodge 
talks  with  "spirits,"  he  does  it  outside  a  physical  laboratory 
and  as  a  misguided  enthusiast,  and  not  as  a  physicist.  To 
talk  of  or  to  ghosts  is  to  talk  of  or  to  a  ghost  story.  Neither 
X-rays  nor  Hertzian  waves  transcend  any  known  laws  of 
physics.  Thought-transference  and  disembodied  spirits 
transcend  all  the  known  laws  of  physics,  nature,  and  common 


Taste  and  smell  organs  are  the  other  two  of  our  four  special 
senses.  Eyes  and  ears  are  somatic  receptors  and  receive  phys- 
ical stimuli,  ether  or  mechanical  waves.  Taste  and  smell 
organs  are  visceral  receptors  and  are  stimulated  by  chemicals 
in  solution;  hence  they  are  called  chemical  receptors.  Smell 
is  also  a  somatic  receptor,  and  as  the  stimuli  for  smell  come 
from  outside  the  body,  the  organ  of  smell,  together  with  the 
organs  for  hearing  and  vision,  is  also  called  exteroceptor,  to 
distinguish  from  proprioceptors  and  inter oceptors  within  the 

But  bear  in  mind  that  "special  sense"  organs  are  not  pri- 



marily  organs  of  special  senses;  they  are  special  receptors 
to  receive  certain  stimuli  from  the  environment.  Through 
adequate  response  to  such  stimuli  we  make  the  adjustments 
necessary  to  maintain  life.  The  adjustments  are  made  only 
after  the  central  nervous  system  has  analyzed  the  stimuli. 
Thus,  to  use  Herrick's  figure,  the  odor  of  ethyl-alcohol  may 
lead  to  action  in  the  great  somatic  effector,  the  motor  mecha- 
nism, to  get  the  alcohol ;  the  odor  of  that  alcohol  in  the  mouth 
may  lead  to  swallowing  it.  The  first  odor  was  an  exterocep- 
tive stimulus  and  led  to  a  distance  or  somatic  reaction;  the 
odor  in  the  mouth  was  an  interoceptive  stimulus  and  led  to 
a  visceral  reaction.  The  discriminating  mechanism  was  the 
central  nervous  system. 

We  have  a  sense  of  taste;  the  organ  of  taste  is  the  tongue. 
Is  it?  Most  of  the  tongue  cannot  taste  anything.  Nor  can 
any  of  it  taste  honey  from  molasses,  black  coffee  from  qui- 
nine, clam  juice  from  beef  broth,  or  an  apple  from  an  onion. 
It  can  feel  fine  distinctions;  it  is  a  better  touch  than  taste  re- 
ceptor. Taste  buds  only  receive  stimuli:  sweet,  on  the  tip 
of  the  tongue;  sour,  at  the  sides;  salty,  at  the  tip  and  sides; 
bitter,  at  the  root.  Only  these  four  qualities:  sweet,  sour, 
salty,  bitter.  The  fine  discriminations  we  make  in  our  mouth 
are  with  the  aid  of  our  olfactory  organ  in  the  nose  and  with 
our  tongue  as  a  tactile  organ.  Tea  and  wine  "tasters'"  are 
tea  and  wine  smellers.  But  there  is  enormous  individual 
variation  in  the  distribution  of  the  taste  buds;  they  may  also 
be  found  in  the  soft  palate,  the  epiglottis,  even  in  the  larynx. 

The  bitter  receptor  is  a  thousand  times  more  delicate  than 
the  salty — because  there  are  more  bitter  poisons  than  salty 
ones?  Why,  then,  should  the  bitter  buds  be  at  the  root  of  the 

Taste  buds  are  receptors  for  chemical  stimuli.  The  sweet 
buds  are  excited  by  sugar;  also  by  chloroform,  lead  acetate, 
and  other  things  no  more  chemically  related  to  sugar  than 
a  rabbit.  There  is  sugar  in  a  rabbit,  none  in  lead  acetate. 
When  the  sweet  bud  is  excited,  it  tastes  sweet;  the  bud  seems 



to  taste  atoms  or  ions.  Even  the  sugar  in  the  blood  may  be 
tasted  by  victims  of  diabetes,  as  may  the  bitterness  of  bile 
by  the  victims  of  jaundice. 

A  catfish  can  taste  almost  all  over  its  body — it  has  taste 
buds  scattered  around  in  its  skin.  Do  things  taste  sweet, 
sour,  etc.,  to  a  catfish? 

We  smell  with  our  olfactory  receptor,  the  lining  of  one  of 
the  seven  small  cavities  in  our  nose.  The  stimuli  are  re- 
ceived on  microscopic  hairs  bathed  in  liquid  and  must  enter 
into  its  solution.  Man,  it  is  said,  has  "lost  the  sense  of  smell." 
At  any  rate,  our  smell  sense  is  miles  behind  a  dog's  and 
probably  not  as  keen  as  a  shark's.  Yet  the  human  nose  easily 
picks  up  the  scent  of  an  almost  inconceivably  small  amount 
of  an  alcohol  derivative  which  smells  like  garlic  and  is  called 

How  small  is  "almost  inconceivably"?  It  requires  a  thim- 
bleful of  air  to  fill  the  cavity  of  the  smell  receptor.  One 
460-billionth  of  a  gram  of  mercaptan  evaporated  in  a  thimble 
of  air  sniffed  up  our  nose  smells  like  garlic.  What  is  the 
nature  of  that  stimulus?  In  that  almost  inconceivably  small 
fraction  of  a  gram  of  vapor  there  are  200,000,000,000  mole- 

Life  smelled  before  there  were  noses.  The  skin  of  the 
humble  sea  anemone  is  peppered  all  over  with  olfactory  re- 
ceptors. No  doubt  the  ameba  smells  and  tastes.  It  must  have 
chemical  receptors.  It  must  distinguish  useful  from  noxious 
molecules.  It  may  know  how  atoms  taste  and  smell.  It  is 
certain  that  a  world  of  environment  acts  on  both  animals  and 
plants  without  tongue  or  nose.  Yet  they  are  sensitive:  they 
respond  to  stimuli.  Human  beings  deprived  of  the  four 
special  senses  manage  to  live  and  to  experience  sensations; 
sensations  arise  in  the  cortex  of  the  brain. 

Of  all  our  special  senses,  smell  sensation  dies  out  quickest. 
The  first  whiff'  is  the  best — or  the  worst  if  it  is  that  kind  of  an 
odor.  If  it  is,  and  dangerous,  move;  in  a  few  moments  it  can 
no  longer  be  smelled.   The  odor  may  last,  the  smell  sensation 



passes.  But  not  the  memory:  some  of  childhood's  vividest 
memories  are  mixed  up  with  the  smell  of  dust,  burning 
brush,  etc. 

While  a  certain  patch  inside  our  nose  and  certain  buds  on 
our  tongue  and  in  our  mouth  are  specialized  for  certain 
chemical  stimuli,  our  skin  and  the  mucous  membrane  of  our 
lips,  mouth,  and  alimentary  canal  can  taste  acids,  mustard, 
and  all  irritating  substances.  In  other  words,  certain  parts 
of  our  body  are  sensitive  to  certain  chemical  stimuli ;  they  are 
less  sensitive  than  the  specialized  end-organs  for  chemical 
stimuli.  For  example,  ethyl-alcohol  in  dilution  strong  enough 
to  be  smelled  must  be  24,000  times  as  strong  to  be  tasted,  and 
80,000  times  as  strong  before  it  excites  the  mucous  membrane 
of  the  mouth. 

In  speaking  of  certain  vestigial  structures  of  our  body, 
reference  was  made  to  Jacobson's  organ  in  the  cartilage  of 
our  nose.  There  is  some  evidence  that  this  vestige  still  func- 
tions as  a  common  chemical  sense  organ.  It  originally  served 
to  smell  food  after  it  was  taken  into  the  mouth  and  was  con- 
nected directly  with  the  mouth.  These  openings  exist  in 
snakes'  mouths  and  receive  the  tips  of  the  forked  tongue;  they 
can  distinguish  odors  from  tastes  of  food  in  the  mouth.  We 
cannot.  For  that  reason  "all  food  tastes  alike"  when  our  nose 
is  stopped  up  with  a  cold. 


Every  human  individual  normal  enough  to  live  beyond  the 
walls  of  an  asylum  lives  because  he  has  an  equipment  by 
which  he  can  keep  on  making  adjustments  to  changing  condi- 
tions. The  adjustments  we  make  as  individuals  are  indi- 
vidual adjustments,  and  they  will  be  determined  by  many 
factors.  But  the  adjusting  mechanism  itself  has  common 

Thus  we  all  are,  and  at  all  stages  of  our  life  are,  sensitive 
to  change.    We  sense  change  by  receptors  which  are  stimu- 



lated  by  change.  But  we  fail  to  realize  the  nature  of  recep- 
tors, or  understand  what  we  sense,  if  we  think  our  special 
sense  organs  are  all  or  are  the  supreme  receptors.  We  think 
of  glands  as  regulators,  and  so  they  are;  of  our  motor 
mechanism  as  effector,  and  so  it  is;  and  of  our  nervous  sys- 
tem as  conductor,  and  so  it  is;  but  they  are  also  receptors. 
Our  entire  body  is  receptive,  even  as  we  are  responsive. 

Kinesthetic  sense:  a  sixth  sense,  it  has  been  called;  or  pro- 
prioceptor, to  distinguish  it  from  the  five  senses  of  sight, 
hearing,  tasting,  smelling,  and  touching — exteroceptors  which 
receive  stimuli  from  without.  By  the  kinesthetic  sense  we 
receive  information  from  within.  Without  that  information 
our  motor  mechanism  would  be  useless,  nor  could  we  ever 
learn  to  talk  or  walk. 

Impulses  arise  in  this  mechanism:  in  muscles,  tendons, 
joints.  All  have  special  sense-organ  structure.  They  respond 
to  pressure.  With  every  contraction  of  muscle  in  talking, 
writing,  walking,  etc.,  pressure  is  exerted  somewhere,  nerve 
impulses  are  released.  As  these  muscles  are  in  opposite  sets 
— to  raise  or  lower  the  arm  or  head,  for  example — we  come 
to  know  where  our  head,  arms,  legs,  fingers,  toes,  etc.,  are 
without  having  to  look. 

We  are  not  conscious  of  these  countless  stimuli,  rarely 
think  of  them  except  in  pain  or  fatigue.  Nor  is  it  easy  to 
define  the  stimulus  which  affects  them,  largely  because  we 
learn  to  use  our  motor  mechanism  very  early  in  life.  But 
they  are  among  our  most  important  sense  organs.  Normally 
our  muscles  are  in  tone,  neither  fully  extended  nor  fully  con- 
tracted. Such  explicit  bodily  movements  as  eating,  drinking, 
talking,  smoking,  walking,  etc.,  function  as  perfect  habits, 
and,  once  acquired,  with  as  little  effort  as  though  they  were 
inherent  habits.  It  is  this  kinesthetic  sense  which  enalDles  us 
to  train  the  motor  mechanism  to  function  so  perfectly. 

The  three  semicircular  canals  in  the  inner  ear  are  most  im- 
portant sense  organs;  by  the  information  diey  furnish  the 
body  learns  to  balance  itself.    Without  them  we  could  not 



orientate  our  body  along  the  line  of  gravity.  Nor  without  the 
supplementary  mechanism  to  the  canals  could  we  keep  our 
head  in  equilibrium  when  the  body  itself  is  at  rest.  Orienta- 
tion is  quite  as  important  as  locomotion. 

There  is  an  organic  sense.  Organs,  tissues,  etc.,  in  thoracic, 
abdominal,  and  pelvic  cavities  are  on  the  autonomic  line  of 
nerves,  but  they  are  also  supplied  by  sensory  (afferent) 
nerves  which  reach  the  central  nervous  system  direct.  Mouth, 
stomach,  heart,  diaphragm,  peritoneum,  and  urogenital  or- 
gans are  especially  sensitive.  Stimuli  from  these  regions 
reach  central  and  initiate  movements  in  the  motor  mechanism. 
Indeed  our  most  intimate  and  personal  reactions  are  in 
response  to  stimuli  originating  in  unstriped  or  visceral  muscle 

We  have  an  "appetite,"  we  are  "hungry,"  "thirsty," 
"sleepy,"  "tired":  these  are  real  senses.  Where  or  what  the 
receptors  for  these  senses  are  is  not  yet  known.  But  we  can 
speak  of  the  viscera  themselves  as  receptors.  Thus  the 
stomach  is  the  "receptor"  or  organ  of  hunger  when  its  muscles 
set  up  hunger  contractions;  the  throat  is  an  organ  of  thirst 
when  its  mucous  membrane  is  dry;  etc.  Herrick  distinguishes 
further:  organs  of  nausea;  organs  of  respiratory,  circulatory, 
and  sexual  sensations;  and  organs  of  sensations  of  distension 
of  cavities  and  of  visceral  pain. 

These  organic  impulses  lead  to  adjustment  reactions:  food, 
water,  sex,  voidance  of  noxious  stimuli,  etc.  They  are  back 
of  life.  Impulses  from  these  unstriped  muscles  must  rouse 
action  in  the  skeletal  or  striped  muscles.  And  so  we  are 
driven  to  seek  water,  food,  make  love,  etc.  If  the  motor 
mechanism  does  not  satisfy  these  organic  impulses,  they  fur- 
nish the  drive  for  emotional  postures  and  attitudes. 

As  many  of  these  organic  impulses  leading  to  bodily  activ- 
ity function  rhythmically,  we  are  supplied  by  our  body  itself 
with  a  reflex  basis  for  a  sense  of  time. 

Our  skin  itself  is  a  marvelous  receptor,  but  it  is  organized 
for  certain  ranges  and  kinds  of  stimuli.   These  excite  special 



nerve  endings  rather  than  special  organs.  One  group  is  sen- 
sitive to  touch  and  mild  degrees  of  temperature.  When 
stimulated  the  sensation  is  felt  as  though  it  belonged  to  the 
objects  themselves.  The  other  group  senses  pressure  and 
pain,  and  heat  above  113  degrees  and  cold  below  68  degrees; 
the  sensations  are  felt  as  on  or  in  the  skin  and  not  as  proper- 
ties of  the  objects  which  excited  the  stimuli. 

Stimulus  to  a  heat  spot  is  felt  as  heat,  never  as  pain.  Pain 
spots  can  be  excited  by  chemicals,  mustard,  acids,  by  cutting, 
pinching,  etc.,  by  electric  current,  by  freezing  or  burning,  and 
by  osmotic  action  such  as  salt  in  an  open  wound.  Whatever 
the  stimulus,  the  pain  spot  registers  pain:  it  hurts! 

And  there  are  paradoxes.  Why  does  menthol  feel  cold 
and  carbon  dioxide  feel  warm  to  the  skin?  Or  a  warm  ob- 
ject feel  cold  when  applied  to  a  cold  spot?  Why  do  we  have 
chills  when  we  have  fever?  We  speak  of  feeling  "cold  to 
the  very  marrow  of  our  bones,"  but  no  temperature  receptor 
has  been  located  within  the  body. 

A  hand  plunged  into  hot  water  presumed  to  be  cold  "feels" 
cold.  A  nurse,  told  to  keep  her  patient's  hand  in  water  as 
hot  as  he  could  "comfortably"  stand  it,  kept  on  applying 
heat.  He  could  stand  it — even  up  to  the  point  where  the  skin 
came  off!  A  frog  shows  greater  ability  to  "get  used  to  it." 
Put  a  frog  in  a  pot  of  cold  water  and  raise  the  temperature 
very  slowly;  the  water  can  be  brought  to  a  boil  without  the 
frog  showing  the  slightest  sign  of  feeling.  In  both  cases  the 
noxious  stimulus  was  too  gradual. 

Suggestion  may  explain  why  the  hand  felt  hot  water  as 
cold,  as  it  explains  the  difference  in  the  sensation  of  a  wisp  of 
cotton  and  a  lock  of  a  girl's  hair  on  one's  brow.  But  sugges- 
tion does  not  explain  the  painless  scalded  hand,  nor  did  it 
keep  the  frog's  mind  at  ease  while  it  got  cooked.  The  hand 
became  adapted;  loss  of  skin  was  the  price.  The  frog  became 
adapted;  it  lost  its  sensitivity  and  its  life.  As  we  do  in  pro- 
longed fever  or  in  starvation. 

"What  hurts,  teaches,"  says  a  Latin  proverb.   That  is  why 



we  have  pain  spots.  That  is  why  when  in  great  pain  we  have 
little  room  for  other  feelings.  A  boy  might  forget  a  toothache 
at  a  ball  game,  but  not  an  earache.  Severe  pain  must  have 
the  right-of-way;  it  is  not  easily  shunted  on  to  a  side  track. 
This  can  be  shown  on  a  dog  whose  brain  has  been  put  out  of 
action.  Stimulation  of  a  pain  spot  and  a  pressure  spot  in  the 
same  region  of  its  leg  excites  two  different  nerves:  one  draws 
the  foot  up  as  though  it  were  wounded,  the  other  extends  the 
foot  as  in  walking.  Both  are  reflex  movements.  But,  obvi- 
ously, the  leg  cannot  be  drawn  up  and  extended  at  the  same 
time.  ^^Hiich  reflex  does  the  brainless  dog  make?  The  one 
which  answers  the  danger  signal,  every  time. 

We  may  be  warned  that  "the  tooth  will  hurt  only  a  tiny 
bit";  we  twinge  just  the  same.  We  jump  in  spite  of  our- 
selves when  we  hear  a  big  gun  fired;  wink,  though  we  know 
the  experimenter's  hand  will  not  reach  our  eye. 

We  have  reflexes  and  reflexes.  Those  which  respond  to 
danger  signals  take  precedence;  they  are  prepotent.  No 
matter  where  it  comes  from  or  what  the  excitation,  whether 
cinder  in  the  eye,  frost  on  the  ear,  or  gas  in  the  intestine, 
pain  is  a  call  for  help.  Unfortunately,  for  many  of  our  pains 
we  have  no  adequate  reflex  response;  we  call  in  the  doctor 
to  become  the  effector  of  the  reflex  arc. 

But  normally  we  are  free  of  pain.  Only  when  this  or  that 
receptor  transmits  a  message  of  greater  intensity  than  the 
nerve  is  accustomed  to  conduct  does  the  message  break  out 
of  its  beaten  path  to  encounter  a  path  of  greater  resistance. 
Any  part  of  our  body  may  be  a  receptor  of  pain.  Even  a 
new  idea  may  be  painful  to  a  brain  cortex  which  is  all 
made  up. 

Life  is  sensitive  to  vital  situations  and  must  respond  to 
meet  such  situations.  But  the  excitability  of  living  beings 
is  not  a  particular  this  or  that;  it  is  an  energy-complex  played 
upon  by  countless  stimuli.  Some  provoke  one  kind  of 
response,  some  another;  most  of  them  none  at  all — no 
response  is  needed.    The  response  must  be  adequate,  of  a 



kind  appropriate  for  carrying  on.  To  classify  receptors 
according  to  the  nature  of  the  stimulus  or  the  kind  of  energy 
which  excites  them,  does  not  tell  us  all  the  avenues  by  which 
the  world  as  stimulus  beats  in  upon  our  body. 

Because  our  receptors  are  specialized  they  are  of  enormous 
importance.  Through  them  we  keep  in  "touch"  with  our 
environment;  we  smell  "the  battle  afar  off,  the  thunder  of  the 
captains,  and  the  shouting."  Through  any  one  of  several 
receptors  we  can  become  excited  by  fire  before  its  heat 
scorches  our  body. 

Through  our  special  senses  we  see,  hear,  smell,  taste,  and 
feel  our  way  through  life  and  learn  of  each  other  and  of  the 
world  in  which  we  live.  They  are  good  enough  for  practical 
purposes,  but  they  fall  short  of  human  ambition.  Science 
sees  with  telescope,  microscope,  fluoroscope,  spectrum,  etc.; 
hears  with  amplifiers:  hears  a  bee  change  its  mind  and  what 
wireless  waves  through  the  ether  say.  Herrick  asks  us  to 
think  of  what  the  world  would  be  to  us  if  our  eyes  were  like 
eagles',  our  noses  as  keen  as  dogs',  and  our  bodies  sensitive 
to  Hertzian  waves.  X-rays  and  the  like,  and  to  other  forms 
of  energy  manifestations  as  yet  unknown  to  us.  As  we  are, 
we  are  earthbound  within  the  limits  set  by  our  physical 
sensory  equipment;  ''nor  can  our  thinking  transcend  the  realm 
of  sense  experience." 


A  fly  lands  on  my  finger:  it  annoys  me;  I  wiggle  my 
finger:  the  annoyance  flies  away.  There  was  a  slight  lapse 
of  time  between  landing  of  fly  and  wiggling  of  finger:  the 
reaction  time,  the  time  required  for  a  stimulus  to  be  answered 
by  a  response.    It  was  about  .05  of  a  second. 

Why  so  much  time?  What  was  I  doing  all  this  time?  / 
had  nothing  to  do  with  it.  I  was  not  conscious  of  the  perform- 
ance; it  happens  also  in  our  sleep.  Had  I  been  conscious  I 
might  have  stopped  the  finger  response  to  admire  the  tiny 



living  airplane  that  had  made  a  perfect  landing.  I  might 
have  given  the  fly  leave  to  study  my  finger  as  long  as  it 
pleased,  wondering  why  my  finger,  of  all  spots  in  the  world, 
stimulated  it  at  that  particular  instant  to  respond  by  landing. 

It  lands:  stimulus.  That  stimulus,  as  impulse,  is  put  on 
an  aff'erent  or  sensory  nerve  for  transmission  to  central.  The 
impulse  can  lead  to  no  response  until  put  on  an  efferent  or 
motor  nerve  ending  in  an  effector,  a  response  mechanism.  In 
only  one  place  can  impulse  be  transferred  from  sensory  to 
motor  nerve:  central  nervous  system — brain  and  spinal  cord. 

All  the  switchboards  of  all  the  centrals  of  all  the  telephone 
systems  on  earth  combined  into  one  would  be  a  simple 
exchange  compared  to  our  own  central  exchange.  This  cen- 
tral, with  the  nerve  trunks  leading  in  and  out  and  the  rami- 
fications of  the  individual  nerves  of  the  trunk  lines  and  the 
ramifications  of  the  branches  of  the  billions  of  individual 
neurons — this  is  our  nervous  system. 

That  fraction  of  a  second  between  excited  finger  and  finger 
wiggle  is  the  time  it  took  for  the  impulse  to  be  transmitted  to 
central,  there  switched  to  another  nerve  to  carry  an  impulse 
back  to  the  finger.  Same  finger.  But  the  impulse  started  on 
the  skin  of  the  finger;  it  ended  in  certain  muscles  of  the  finger. 

Reflex  action;  there  is  a  reflex  arc;  but  central  fills  the 
breach  in  that  arc.  The  skin  of  finger  cannot  talk  to  muscles 
of  finger.  Skin  can  inform  central,  central  can  give  orders 
to  muscles.  Every  message  that  comes  to  us  from  outside 
the  body  is  carried  to  central,  every  response  to  such  messages 
is  directed  from  central. 

The  .05  of  a  second  for  that  reflex  assumes  that  the 
response  was  automatic:  that  it  was  a  true  reflex,  that  my 
conscious  self  had  no  part  in  it.  Several  factors  enter  into 
reflex  time.  Had  the  fly  been  a  red-hot  coal  the  time  would 
have  shortened :  a  vital  stimulus  gets  a  more  prompt  response. 
Reflex  time  is  also  conditioned  by  the  nature  of  the  stimulus : 
we  respond  more  promptly  to  sound  than  to  light.  A  third 
factor  is  the  number  of  synapses  that  must  be  passed.  They 



seem  to  act  as  switches  or  relay  stations  to  control  the  direc- 
tion of  impulses — at  one  time  open  for,  at  another  time 
blocking,  conduction. 

The  physical  contact  of  fly  on  finger  skin  called  out  the 
reflex.  But  the  sight  of  the  fly  or  the  sound  of  its  wings 
could  have  led  to  the  same  reflex.  In  other  words,  any  one 
of  several  distinct  kinds  of  receptors  might  be  excited  by  the 
fly  and  lead  to  the  same  reflex.  The  messages  are  distinct: 
one  from  eye,  another  from  ear,  another  from  skin;  the 
answer  from  central  may  be  the  same. 

I  was  stretched  out  on  a  blanket  under  a  tree  in  Colombia, 
sound  asleep — noonday  siesta.  I  suddenly  found  myself  on 
my  feet — and  a  long  green  snake  in  front  of  me.  I  was 
unaware  of  awakening  or  of  getting  to  my  feet,  or  of  having 
seen  the  snake  until  that  instant. 

What  had  been  the  stimulus?  My  companion,  dozing  on 
his  blanket  a  dozen  feet  away,  had  turned  over  just  as  the 
snake  was  crawling  across  my  chest.  He  yelled,  "Snake!" 
I  jumped  to  my  feet.  My  whole  body  could  perform  a  reflex 
action  before  my  conscious  self  could  take  charge  of  the 
situation  and  make  human  response:  kill  the  snake.  A 
cultural  reaction.  Had  my  interest  been  ophidia  and  not 
ethnology,  my  behavior  would  have  been  diff'erent.  Brought 
up  as  a  Hindu  and  without  influence  of  Serpent-Eve  tradition, 
that  snake  would  be  alive  to-day,  for  all  of  me. 

Something  happens  to  messages  from  the  outside  world 
when  delivered  to  central.  The  word  snake  might  have  led 
to  the  same  impulsive  reflex — an  avoiding  response;  but  the 
messages  already  handled  by  central  determined  my  reaction 
to  that  particular  message.  We  come  to  have  reaction  pat- 
terns, complexes  of  behavior.  We  condition  our  reflexes; 
we  condition  ourselves.  Our  nervous  system  itself  becomes 
conditioned,  is  conditioned,  day  by  day,  from  birth.  The 
conditioning  factors  are  environment — an  East  Side  tenement 
or  the  Babbitts  of  Main  Street. 

In  other  words,  what  behaves  is  not  brain  nor  central 



nervous  system  nor  reflex  arc,  but  this  boy,  that  girl,  this 
woman,  that  man,  integrated  by  an  integrating  organ,  adjust- 
ing through  an  adjusting  mechanism.  Behavior,  like  life, 
resides  in  individual  packages.  The  response  of  a  crowd 
may  be  more  intense;  even  as  one  wolf  hesitates  to  tackle  a 
lion,  but  as  one  of  a  pack  takes  a  chance.  Crowd  and  pack 
behavior  occur  because  man  and  wolf  vary  their  response 
with  the  nature  and  intensity  of  the  stimulus. 

The  business  of  the  central  nervous  system  is  to  regulate 
and  adjust  behavior  according  to  the  nature  of  the  stimulus. 
Few,  if  any,  tissues,  structures,  organs,  glands,  muscles,  or 
vessels  of  the  body  are  beyond  its  reach.  Our  vegetative 
processes  normally  go  on  without  conscious  thought,  nor  can 
we  control  them  by  our  "will."  But  let  one  of  these  processes 
go  on  a  strike,  central  knows.  Knows  because,  as  all  roads 
led  to  Rome,  all  nerves  end  in  central.  All  nerves  deliver 
their  messages  to  central.  Central  is  responsible  for  the 
behavior  of  the  individual. 

Certain  nerves  end  here,  others  there.  There  are  centers 
for  this,  centers  for  that.  But  central  functions  as  a  unit;  it 
functions  for  a  unit — the  individual.  Nerves  so  knit  together 
all  parts  of  the  body  that  central  can  organize  the  body  as  a 
whole  for  life — and  finds  ways  out  of  difficulties  that  baffle 

A  child  is  born  deaf,  dumb,  and  blind.  What  kind  of 
mental  life  is  within  its  reach?  That  was  Helen  Keller's 
fate.  Yet  her  mental  development  was  astounding  and  little 
less  than  miraculous. 


A  snowball  aimed  at  me  hits  a  dog.  The  dog  jumps,  yelps, 
and  runs.  The  next  ball  hits  me.  Can  you  predict  my 
behavior,  as  I  do  the  dog's?  I  cannot.  I  might  jump,  yelp, 
and  run;  I  might  make  no  outward  response.  Ten  years 
later  I  might  marry  the  girl  who  threw  the  ball ;  or  forty  years 



later  read  with  dry  eye  that  the  boy  who  threw  it  had  killed 
himself  with  wood  alcohol. 

The  message  from  snowball  was  delivered  to  the  spinal 
cord.  The  cord  could  answer  it  by  making  certain  bodily 
adjustments.  Meanwhile  the  medulla  had  been  informed  and 
was  ready  to  contribute  to  the  reaction ;  by  a  wink  or  a  sneeze 
or  a  cough,  or  orders  to  heart  or  blood  vessels  to  prepare  for 

What  action?  What  next?  Here  is  where  the  10,- 
000,000,000  neurons  of  the  cerebral  cortex  get  into  the 

Spinal  cord  and  brain  stem  (chiefly  medulla)  are  the  two 
lower  divisions  of  the  central  nervous  system.  Cerebellum 
and  cerebrum  are  the  two  higher.  The  cerebrum  itself  is  the 
supreme  central;  larger  in  man  in  proportion  to  weight  of 
body  or  of  spinal  cord  than  in  any  other  animal;  it  is  evolu- 
tion's latest  improvement  as  central  of  a  central  nervous 

The  eighteen  inches  of  spinal  cord  is  central  for  a  few 
important  automatic  reflexes  and  receives  the  thirty-one  pairs 
of  spinal  nerves  which  supply  skin,  motor  mechanism,  and 
parts  of  the  viscera.  It  ends  in  and  is  intimately  connected 
with  the  brain,  which  consists  of  the  other  tliree  divisions  of 
central:  brain  stem;  cerebellum  (little  brain);  cerebrum 

The  medulla  of  the  brain  stem,  an  enlargement  of  the 
spinal  cord  just  inside  the  skull,  is  probably  the  busiest  center 
of  central.  Here  end  all  but  four  of  the  twelve  cranial 
nerves;  through  here  almost  all  impulses  pass  from  one 
division  of  central  to  another.  Every  mark  I  make  with  my 
pencil  has  first  traversed  the  medulla.  It  is  also  a  real  central 
of  its  own,  the  center  for  such  important  reflexes  as  winking 
(in  part),  sneezing,  coughing,  chewing,  sucking,  swallowing, 
vomiting,  and  the  secretion  of  saliva  and  gastric  juice.  It  is 
also  the  center  for  breathing,  for  regulating  the  size  of  the 



blood  vessels,  and  for  speeding  up  and  slowing  down  heart- 

The  medulla  is  only  one-twentieth  of  the  weight  of  the 
entire  brain — and  hollow  at  that!  How  does  it  control  so 
many  vital  functions?  By  receiving  impulses  and  setting  this 
or  that  mechanism  at  work.  I  step  into  a  tub  of  cold  water. 
The  cold  receptors  of  the  foot  transmit  the  news  to  a  center 
in  the  medulla,  the  medulla  orders  the  blood  vessels  of  the 
skin  to  close  in:  there  is  an  enemy  to  proper  body  temperature 

And  so  it  works.  On  behalf  of  the  medulla?  No;  on 
behalf  of  the  body.  The  body  is  always  adjusting  itself:  to 
bad  air,  to  poor  food,  to  cold  water,  to  thirst,  to  fleas  and 
flies,  to  summer  and  winter,  to  tight  shoes  and  high  collars 
and  corsets,  and  countless  other  frills  and  fads  listed  in 
civilization's  catalogue. 

The  catalogue  is  prepared  in  the  higher  centers  of  central. 
We  can  live  with  a  bullet  hole  in  the  "higher  centers";  a 
bird-shot  in  the  medulla  stops  the  heart. 

While  sitting  in  a  chair  or  walking  about  the  little  brain 
center  is  in  control.  The  chief  function  of  the  cerebellum 
is  to  keep  us  right  side  up.  This  is  more  important  for 
fishes  and  birds  than  for  some  men,  and  more  difficult  for 
men  than  for  any  quadrupeds.  But  all  vertebrates  have  a 
well-developed  cerebellum.  To  preserve  our  balance  and 
adjust  our  equilibrium  is  an  enormously  involved  process. 
No  wonder  the  cerebellum  is  convoluted  and  covered  with 
gray  matter.  Probably  1,000,000,000  neurons  take  part  in 
every  move  we  make  to  keep  straight.  To  the  cerebellum 
come  messages  from  the  pressure  receptors  in  our  feet,  from 
the  receptors  in  all  joints,  tendons,  ligaments,  and  muscles, 
from  the  sight  receptors  of  our  eyes,  and  especially  from  the 
position  and  motion  receptors  of  our  inner  ears.  The  cere- 
bellum correlates  and  co-ordinates  these  messages;  adjust- 
ments are  thus  made  possible.  We  can  walk  like  a  man,  or 
swim  like  a  fish,  or  fly  like  a  bird. 



A  blindfolded  person  maintains  his  equilibrium  with 
difficulty:  the  cerebellum  is  denied  one  important  source  of 
information  needed  to  adjust  the  body.  The  blind  man 
learns  to  preserve  his  balance.  Every  movement  of  his  motor 
mechanism  registers  in  the  cerebellum ;  the  motor  mechanism 
itself,  in  whole  and  in  detail,  is  a  receptor.  The  cerebellum 
interprets  messages  from  this  sensory  field. 

The  claim  has  recently  been  made  by  Japanese  neurologists 
that  the  cerebellum  also  co-ordinates  movements  of  tongue, 
lips,  and  vocal  cords,  and  therefore  regulates  speech.  In 
that  case  it  is  both  balancing  and  talking  brain. 


Spinal  cord;  mid-brain;  cerebellum;  higher,  higher, 
higher.  Further  away  from  the  simple  life.  But  as  the 
spinal  cord  is  the  region  which  contains  the  mechanism  for 
effecting  many  reflex  actions,  so  the  whole  central  nervous 
system  is  the  region  for  the  mechanism  for  effecting  all 
actions  and  reactions.  The  brain  differs  from  the  cord  only 
in  the  fact  that  it  contains  more  and  longer  reflex  arcs  or 
nerve  paths  and  more  numerous  connections.  Centers  are 
regions  where  diverse  impulses  can  be  co-ordinated  and 
appropriate  adjustments  thereby  become  possible.  There 
are  higher  and  higher  centers.  The  cerebrum  is  the  highest 
or  supreme  adjuster. 

In  a  well-filled  head  the  cerebrum  does  most  of  the  filling; 
and  what  the  icing  is  to  a  cake  the  gray  matter  is  to  the 
cerebrum.  This  gray  matter  is  called  cortex  because  it  is 
the  bark  of  the  cerebrum.  The  cortex  is  also  found  on  the 
cerebellum  and  inside  the  medulla  and  spinal  cord.  It  is 
made  up  of  actual  neuron  bodies  and  their  synapses — ^hence 
its  color,  gray.  White  matter  contains  the  fibers  or  conduct- 
ing structure  of  neurons.  Because  of  the  many  deep  infold- 
ings  or  convolutions  of  the  brain,  the  gray  matter  contains 
enormous  numbers  of  neurons.    Degeneration  of  that  gray 



matter,  whether  from  syphilitic  "general  paralysis  of  the 
insane"  or  from  other  causes,  ends  in  death. 

We  walk  through  life  like  men  because  we  are  human 
beings  and  our  motor  mechanism  calls  for  an  upright  body 
balanced  on  two  legs,  one  of  which  must  be  off  the  ground 
half  the  time  we  are  walking.  Meanwhile,  to  preserve  that 
gait,  all  our  body  weight  except  that  of  one  leg  is  delicately 
balanced  on  a  ball  half  the  size  of  a  billiard  ball.  This  is 
a  very  clever  trick  and  requires  many  months  to  learn,  during 
which  we  get  many  hard  falls.  Once  learned,  we  do  it  with- 
out effort  the  rest  of  our  life,  provided  we  keep  sober  and 
receive  no  injury  to  our  cerebellum. 

Injury  to  the  cerebellum  need  not  be  fatal  but  does  throw 
us  off  our  stride.  We  stagger  about  and  in  general  suffer 
from  lowered  muscle  co-ordination.  But  we  can  get  over 
this.  The  stagger  need  not  be  permanent,  though  the  injury 
to  the  cerebellum  is.  Why? 

The  cerebrum  has  taken  over  the  function.  This  is  the 
clue  to  cerebrum.  It  is  neither  special  organ  nor  performs 
special  function :  it  can  learn  to  do'  anything.  Its  capacity 
is  incalculable.  Its  switching  capacity  alone  runs  into 
figures  which  make  German  marks  look  like  gold  coin  and 
distances  between  stars  like  diameters  on  a  mile  track. 

It  is  because  of  cerebral  gray  matter's  range  of  behavior 
permutations  that  a  Greek  professor  could  devote  a  lifetime 
to  the  solution  of  a  new  diacritical  mark  on  an  ancient  manu- 
script— to  discover  just  before  he  died  that  it  was  a  fly  speck. 

A  child  born  without  cerebrum  lived  four  years.  It  pre- 
served the  reflexes  it  was  born  with :  sucking,  crying,  sneezing, 
grasping,  etc.  It  never  learned  to  recognize  its  mother  nor 
how  to  hold  a  bottle.  It  never  learned  any  controlled  or 
voluntary  motions.  It  would  lie  for  hours  and  hours  in 
unchanged  position.  Of  nervous  or  mental  growth  there  was 
none,  of  intelligence  less  than  that  of  a  decerebrate  frog. 

If  the  cerebrum  must  be  labeled,  call  it  the  organ  of  asso- 



dative  memory  and  the  structural  foundation  of  human 

The  cortex  of  the  cerebrum  is  a  clearing-house,  or,  as  Child 
calls  it,  "a  deliberative  assembly  to  which  reports  of  matters 
requiring  consideration  come  in  from  the  various  groups  or 
bureaus  and  in  which  they  are  considered  and  action  taken 
through  the  proper  channels."  But  before  they  enter  this 
highest  court  they  must  pass  one  or  more  of  the  lower  correla- 
tion centers. 

In  other  words,  with  a  toothache  on  my  mind  the  snowball 
that  hits  me  is  relatively  unimportant  and  gets  scant  attention 
from  me,  and  could  be  answered  by  a  mere  jump  reflex.  But 
under  ordinary  conditions  the  stimulus  of  snowball  reaches 
the  cerebrum.  Then  I  become  conscious;  this  or  that  region 
of  the  cortex  is  intensely  active;  connections  are  made  with 
other  regions.  A  conflict  goes  on;  the  solution  of  the  conflict 
will  determine  my  reaction.  Hesitation  on  my  part  means 
that  the  problem  is  not  yet  resolved.  When  a  decision  is 
reached,  reaction  follows.  While  the  matter  is  being  adjusted 
a  boy  knocks  my  hat  off".  This  also  reaches  the  cortex:  the 
lower  centers  cannot  make  adequate  response  to  such  an 
insult!  Another  region  of  the  cortex  becomes  the  scene  of 
violent  activity. 

Consciousness  at  this  or  that  moment,  then,  is  determined 
by  the  field  of  our  cortex  at  the  moment  active:  impulses  have 
come  in  which  must  be  answered  and  which  cannot  be 
answered  except  with  the  aid  of  the  cortex.  Only  the  cortex 
has  the  complete  files  of  all  that  has  gone  before.  Only  the 
cortex  can  hear  all  the  evidence  from  all  the  body:  eyes, 
ears,  and  the  million  and  one  receptors  of  a  body  which  itself 
is  receptor  and  eff'ector  and  which  in  consciousness  calls  upon 
the  superadjustor  cortex  to  govern  its  behavior.  If  a  stimulus 
is  not  of  enough  importance  to  require  cortex  adjustment, 
it  is  not  strong  enough  to  get  into  consciousness. 

What  messages  reach  the  cortex:  odor  of  a  bad  egg,  burst 
of  thunder,  flash  of  lightning,  taste  of  a  quinine  pill,  feel  of 



a  red-hot  poker,  sting  of  an  insult,  colic,  toothache?  They 
do,  but  they  cannot  reach  the  cortex  direct.  As  Herrick 
points  out:  "No  simple  sensory  impulses  ordinarily  reach 
the  cortex,  but  only  nervous  impulses  arising  from  the  lower 
correlation  centers."  Of  all  the  messages  that  reach  the  cor- 
tex, those  from  the  eyes  are  the  purest:  they  have  less  sub- 
cortical matter  to  deal  with  first.  "It  is  no  accident  that  the 
visual  sense  plays  a  dominant  role  in  human  cortical 

That  the  lower  courts  of  the  body  can  perform  so  many 
living  functions  so  well  is  why  so  little  is  referred  to  the 
supreme  cortex  adjustor,  and  also  explains  why  so  many  have 
nothing  to  think  about:  their  body  does  their  thinking  for 


Gall,  a  Viennese  surgeon,  was  the  first  to  suggest  that  the 
cerebrum  or  brain  proper  is  a  group  of  organs,  each  perform- 
ing a  separate  function.  Out  of  that  suggestion  grew 
phrenology  and  nonsense  and  finally  a  disregard  for  the 
cerebrum.  No  one  disregards  the  cerebrum  nowadays,  except 
under  penalty  of  losing  control  of  all  that  distinguishes  man 
from  his  lowest  ancestors.  The  cerebrum  is  a  single  organ, 
not  yet  well  understood,  but  known  to  be  the  most  complex 
structure  yet  thrown  up  by  the  100,000,000  years  of  evolving 

Real  individuality  in  life  begins  with  the  cerebrum.  The 
less  cerebrum,  the  less  power  to  learn.  The  greater  the 
cerebrum,  the  greater  the  capacity  to  learn  from  experience. 
Of  all  the  structures  man  has  inherited,  he  knows  least  about 
the  one  which  made  human  culture  possible;  and  because  he 
has  used  it  least,  human  civilization  has  become  the  senseless 
thing  that  it  is. 

A  lion  can  learn  to  lie  down  beside  a  lamb,  but  a  moth 
cannot  learn  to  let  a  flame  alone.   The  moth  has  no  cerebrum. 

The  cerebrum  is  one  organ,  but  is  the  central  for  several 



centers  or  areas  of  motor  and  sensory  function.  These  areas 
are  connected  by  association  areas,  large  regions  of  the  brain 
cortex  which  have  no  direct  connection  with  the  brain  stem, 
and  stimulation  of  which  leads  to  no  known  effect.  They  are 
as  yet  the  unknown,  the  great  silent  fields;  the  "deepest  mys- 
tery" of  the  brain,  Mitchell  calls  them.  They  are  the  neiv 
parts  of  the  brain:  "probably  blanks  at  birth  and  upon  them 
is  recorded  the  story  of  a  lifetime."  At  any  rate,  without 
them  we  could  learn  no  new  habits,  no  conditioned  reflexes, 
nor  become  intelligent  human  beings. 

The  sensory  areas  for  sight,  hearing,  and  smell  are  def- 
initely located  on  the  cerebrum.  The  taste  areas  are  not  well 
known.  The  skin  and  kinesthetic  sense  areas  are  known; 
they  are  at  the  endings  of  the  afferent  paths  from  skin, 
viscera,  muscle,  and  skeleton  receptors.  A  pain  area  has  not 
been  localized. 

The  following  motor  areas  have  been  localized:  face,  body, 
opening  of  jaws,  closing  of  jaws,  mouth,  tongue,  neck,  vocal 
cords,  nose,  eyelid,  ear,  chest,  shoulder,  arm,  elbow,  wrist, 
fingers,  trunk,  hip,  leg,  knee,  ankle,  foot,  toes. 

Which  means  that  injury  to  a  certain  small  spot  on  your 
brain  cortex  puts  your  toes  out  of  commission.  Your  right 
thumb  is  paralyzed :  injury  in  the  cortex  of  the  left  cerebrum. 
But  when  a  deformed  limb  wastes  away,  it  means  that  tlie 
lower  motor  neurons  of  the  peripheral  nerves  are  destroyed. 

Look  again  over  the  list  of  motor  areas  localized.  How 
many  of  these  structures  can  you  see  with  your  eyes?  Those 
localized  motor  areas  of  the  brain  cortex  are  called  the  pic- 
tured movement  areas.  You  wiggle  your  thumb:  do  your 
eyes  see  the  muscles  involved?  No  more  does  the  brain  see 
or  know  anything  of  muscle.  It  knows  muscle  sensation 
because  it  receives  impulses  from  movement  in  muscles.  It 
knows  thumb  movements  through  the  eyes.  As  Woods  Jones 
puts  it,  the  cortex  comes  to  have  a  vast  store  of  knowledge 
of  concrete  movements,  not  only  of  thumb,  but  of  every  move- 
ment the  body  makes  that  the  eyes  can  see. 



No  repeated  pictured  movements  ever  become  reflexes. 
They  must  be  initiated  in  the  cortex  of  the  cerebrum.  With 
one-half  of  the  brain  cortex  injured,  we  cannot  walk  or  per- 
form any  voluntary  or  pictured  movements  with  the  other 
half  of  the  body.  With  all  the  motor  areas  injured,  there 
is  no  learned  action  in  the  motor  mechanism;  certain 
reflexes  only  may  remain  intact. 

The  baby  learns  to  put  its  finger  on  its  foot,  to  put  its  toe 
in  its  mouth,  to  walk,  to  make  all  purposive  pictured  move- 
ments, through  the  conditioning  of  and  learning  made  possi- 
ble by  the  association  areas  of  the  brain  cortex.  The  cortex 
itself  is  the  receptive  area  for  diff'erent  impressions.  In  the 
association  areas  they  are  sorted,  stored,  blended. 

Thus,  early  conduct  is  pictured  in  terms  of  action.  The 
child  really  begins  to  organize  its  motor  mechanism  when  it 
has  memories  of  past  movements.  It  can  then  begin  to  form 
pictured  concepts  of  possible  future  movements.  A  little 
later  it  can  estimate  its  ability  to  make  movements.  And 
with  this  ability,  we  have  dawning  consciousness  and  youth- 
ful ideals  of  conduct. 

Davenport  speaks  of  his  nine-months-old  son:  "He  cannot 
talk,  dress  himself,  or  attend  to  his  animal  needs.  He  is 
word  and  figure  blind,  cruel  to  the  cat,  appropriates  others' 
property,  and  wants  everything  at  the  inconvenience  of  others. 
He  is  a  low-grade  imbecile  without  moral  ideals."  Which 
simply  means  that  of  altruistic  behavior  we  have  none  at 
birth  and  gain  none  in  the  first  nine  months. 

Insanity  is  a  disorder  of  conduct.  The  pictured  move- 
ment area  of  the  brain  has  gone  out  of  action.  The  body 
does  not  track:  one  part  goes  one  way,  another  part  does  not 
go  at  all.  Impulses  from  all  the  diff'erent  parts  of  the  body 
no  longer  have  a  meeting  place  where  they  can  be  co-ordi- 
nated, and  as  a  result  of  such  co-ordination  adjust  the  body 
as  an  individual  unit. 

The  ideals  of  conduct  conditioned  in  the  growing  brain 



will  have  much  to  do  with  the  roads  that  will  be  open  or 
closed  to  the  adult  brain. 

The  blind  boy's  brain  has  its  pictured  movement  areas, 
only  the  "pictures"  the  eye  sees  must  be  supplied  through 
the  aid  of  other  sensory  organs.  But  no  sense  plays  such  a 
role  in  human  affairs  as  the  visual.  No  impulses  are  deliv- 
ered to  the  cortex  with  so  little  delay  or  pass  so  few  sentinels 
en  route  as  those  from  the  eyes. 

But  to  take  localization  areas  too  literally  is  to  overlook 
the  real  functions  of  the  cerebral  cortex.  They  are  associa- 
tional  rather  than  specific.  The  cerebrum  is  a  superimposed 
center.  It  takes  on  habits — localized  centers  presumably 
thereby  come  into  being;  but  it  can  form  new  habits.  It  is 
the  dominant  center  only  when  the  lower  centers  fail  or  dis- 
agree. But  no  area  of  the  cortex  is  the  exclusive  center  of 
this  or  that  or  of  any  particular  function.  The  centers  of  the 
so-called  sensory  and  motor  areas  are  merely  "nodal  points," 
as  Herrick  calls  them,  "in  an  exceedingly  complex  system 
of  cells  and  fibers  which  must  act  as  a  whole  in  order  to 
perform  any  function  whatsoever."  In  any  other  sense,  a 
cortical  center  for  the  performance  of  a  particular  function 
is  an  absurdity. 

Herrick  distinguishes  two  prime  functions  of  the  cortex. 
First,  correlations  of  great  complexity  and  with  many  diverse 
factors;  of  value  because  of  the  capacity  for  choice  between 
many  possible  different  reactions  to  the  situation.  Next, 
retentiveness  of  past  individual  impressions  in  such  form  as 
to  permit  of  being  recalled  later  and  incorporated  into  new 
stimulus  complexes.  This  is  a  high  type  of  organic  memory; 
it  makes  for  modifiability  of  behavior.  The  mechanism  of 
correlation  functions  may  be  innate;  the  retentiveness  or 
"memory"  function  is  presumably  acquired  after  birth  and 
is  the  supreme  factor  in  the  education  of  human  beings. 
With  the  correlation  function  we  are  enabled  to  give  expres- 
sion to  our  original  nature;  with  the  memory  function  we 
can  modify  our  innate  tendencies  and  take  on  the  trappings 



of  the  culture  which  happens  to  be  the  fashion  in  our  own 
home  town. 


The  first  raisin  I  bit  into  was  wrapped  around  a  quinine 
pill.  About  that  time  I  traded  a  jackknife  for  a  chunk  of 
chocolate,  which  I  devoured  on  the  spot — and  got  sick.  I 
was  thereby  prejudiced  against  two  people  and  thereafter 
disliked  two  things.  I  can  recall  no  detail  of  the  chocolate 
or  raisin  incident;  I  only  know  that  the  sight  of  chocolate 
is  disagreeable,  the  odor  of  a  raisin  unpleasant. 

I  left  a  dark  kitchen  in  a  hurry  and  nearly  split  my  head 
on  an  outstretched  pump  handle.  The  pump  was  removed. 
Twenty  years  later  I  returned  to  that  house.  Leaving  the 
dark  kitchen  that  night,  I  ducked  the  pump  handle  and  was 
conscious  of  a  tingling  sensation  on  my  forehead.  I  had 
forgotten  the  pump:  my  body  had  not  forgotten  the  handle. 
Even  now,  I  sometimes  feel  queer  when  I  leave  that  kitchen 
in  the  dark. 

There  are  two  kinds  of  memories:  one  is  built  into  the  body 
reaction-system  and  generally  is  beyond  recall;  the  other  is 
conscious  memory  and  presumably  entangled  in  the  meshes 
of  the  neurons  of  the  brain  cortex. 

I  may  search  all  day  through  these  neurons  for  a  mislaid 
name.  The  next  morning  I  hear  some  one  whistling  "Annie 
Rooney";  the  name  pops  into  my  head:  Rooney!  Conscious 
effort  failed  to  stimulate  the  "Rooney"  cells:  the  whistled 
tune  excited  the  right  spot. 

Every  neuron  has  potential  connection  with  every  other 
neuron  of  the  nervous  system.  The  connection  may  be  incal- 
culably indirect;  the  paths  are  there. 

A  look,  a  smile,  a  dimple,  may  excite  a  thousand  sparks  to 
fire,  a  thousand  million  neurons  to  activity.  The  total 
reaction  will  be  the  product  of  untold  individual  reactions, 
each  complex.    Every  one  of  these  reactions  modifies  the 



reaction-system.  It  is  not  that  we  pile  up  experiences,  but 
that  experiences  themselves  both  change  the  nature  of  the 
system  and  are  themselves  determined  by  the  nature  of  the 

The  first  "dimple"  we  experienced  in  life  may  have  been 
wrapped  around  a  quinine  pill  or  too  much  chocolate;  we 
are  thereby  "conditioned"  against  dimples. 

Pawlow's  classic  experiments  on  dogs  laid  the  foundation 
for  an  understanding  of  the  conditioned  or  psychic  reflex. 
By  an  ingenious  mechanical  device  he  could  determine  when 
and  how  much  a  dog's  mouth  waters:  a  reflex  action  of  the 
salivary  glands.  This  reflex  normally  takes  place  when  the 
hungry  animal  sees  or  smells  food. 

A  dog  fed  by  one  certain  person  only  secretes  saliva  when 
this  person  appears.  The  sight  of  the  person  sets  off  the 
reflex  mechanism:  there  may  be  no  food  in  sight.  Another 
dog,  fed  only  when  a  certain  musical  note  is  sounded,  even- 
tually shows  mouth  water  whenever  it  hears  that  particular 
note.  If  the  note  were  one  of  1,000  vibrations  per  second, 
a  note  of  960  or  of  1,100  vibrations  calls  out  no  response. 
Another  dog  easily  learned  to  distinguish  110  beats  per 
second  from  100  beats  per  second  of  a  metronome. 

A  dog  is  fed  exactly  two  minutes  after  a  bell  is  sounded. 
Its  mouth  waters  just  two  minutes  after  the  bell  sounds;  this 
is  both  a  conditioned  and  a  delayed  reflex.  Many  persons 
can  "set"  themselves  and  dispense  with  an  alarm  clock.  I 
invariably  anticipate  an  alarm  clock  by  about  three  minutes. 
The  nervous  system  itself  can  keep  time. 

Another  dog  was  always  fed  with  a  ringing  bell  or  a 
flashing  light :  no  food  when  both  stimuli  were  present.  Now 
note.  The  dog's  mouth  begins  to  water  when  the  bell  begins 
to  ring;  while  the  bell  is  still  ringing  the  light  is  flashed;  the 
flow  stops:  light  and  bell  are  no  stimulus. 

We  go  through  that  countless  times  in  our  lives.  Suddenly 
lose  our  appetite — for  innumerable  things  besides  food.  A 
stimulus  which  calls  forth  a  voiding  or  conflicting  reaction 



inhibits  a  previous  stimulus.  We  "lose"  our  appetite:  for 
a  man  who  betrays  us,  a  woman  who  deceives  us.  A  hair 
in  the  soup  shuts  down  many  a  salivary  gland,  a  worm  in  the 
salad  ends  many  a  meal. 

Another  dog  was  fed  with  a  painful  electric  shock  at  a 
particular  spot  on  his  leg.  He  learned  to  like  it.  With  no 
food  in  sight,  his  mouth  would  water  with  the  shock.  The 
same  shock  an  inch  away  from  the  accustomed  spot  brought 
pain  but  not  salivary  reflex. 

For  "dogs"  read  "human  beings";  especially,  "children." 

Destruction  of  this  or  that  area  of  the  cerebral  cortex 
wipes  out  such  conditioned  reflexes  as  are  dependent  on  the 
mechanism  of  the  area  destroyed.  Destruction  of  all  the 
cortex  washes  out  all  conditioned  reflexes. 

Conduction  paths  develop  with  us.  They  get  well  worn 
with  use,  rooted  in  habit.  Paths  that  conduct  pain  impulses 
to  central  may  finally  fail  to  deliver  "pain"  messages  because 
they  have  grown  accustomed  to  carry  such  messages  to  the 
salivary  glands  or  to  the  gonads;  the  impulse  which  should 
have  registered  as  pain  sets  up  or  heightens  activity  in  food — 
or  sex-hunger  mechanism. 

A  smile  may  stimulate  a  miser  to  tighten  his  grasp  on  his 
purse;  but  he  must  be  a  rank  dyspeptic  in  whom  the  sound 
of  the  words:  "Let's  eat!"  provokes  no  conditioned  reflex 
of  salivary  glands. 


We  get  more  energy  per  fuel  unit  from  our  own  internal- 
combustion  engine  than  from  any  engine  we  can  make,  but 
our  body  uses  up  75  per  cent  of  it  and  says  nothing  about 
it.  That  only  leaves  us  with  a  quarter  of  the  energy  we 
transform  from  food  for  consciousness.  But  that  is  enough. 
The  vitally  important  functions  of  life  go  on  as  uncon- 
cernedly as  though  Nature  had  never  invented  nerves  nor 
evolved  brains. 



The  heart  is  the  star  performer.  Remove  it  from  the  body, 
strip  off  its  nerves:  in  a  nutrient  solution  it  keeps  on  beating. 
Cut  a  sliver  from  it :  the  sliver  keeps  on  beating.  The  embryo 
chick's  heart  begins  to  beat  before  nerves  find  it.  The  heart 
is  muscle,  striated  as  are  ordinary  muscles,  but  involuntary, 
as  are  the  muscles  of  the  viscera  and  blood  vessels.  "Invol- 
untary" muscle  is  automatic:  contracts  and  expands  on  its 
own.    Rhythmic  movement  is  inherent  in  such  tissues. 

These  internal  movements — of  heart,  countless  muscles, 
miles  of  arteries,  arterioles,  veins,  venules  and  capillaries, 
and  big  glands  and  little  glands — all  keep  plugging  away 
in  the  dark.  We  cannot  will  them  to  stop.  Nor  by  conscious 
effort  can  we  slow  down  the  heart  or  open  the  valves  that 
control  the  progress  of  food  through  the  alimentary  canal, 
or  stimulate  the  adrenals  to  give  the  blood  a  few  molecules 
of  its  magic-working  hormone. 

"Involuntary":  yes,  beyond  volition.  Automatic:  no. 
Man  is  no  automaton;  nor  is  heartbeat  or  gland  activity  or 
any  process  of  life  "automatic."  Living  processes  are 
responses  to  food  and  oxygen;  matter  is  transferred,  energy 
is  unleashed.  But  some  living  processes  have  learned  their 
lesson  so  well  they  seem  automatic  to  us,  who  must  puff  and 
blow  before  we  reach  the  crest.  Even  if  we  decide  to  give 
up  and  sigh  no  more,  the  most  we  can  do  is  give  up  conscious- 
ness for  a  moment:  the  lungs  will  sigh  out  our  excess  carbon 
dioxide  for  us.  We  may  cry:  "Give  us  air!"  but  life  learned 
to  get  air  millions  of  years  ago.  We  may  demand  our  place 
in  the  sun,  but  life  learned  to  climb  to  the  sun  millions  of 
years  before  man  was  dreamed  of. 

Life  is  motion.  The  capacity  to  move  in  response  to  life's 
heeds  resides  in  all  living  things — ^has  always  resided  in  life, 
is  inherent  in  life.  Life  must  move  to  keep  in  touch  with  the 
air  and  water  and  food  of  life.  Man  and  higher  animals 
have  taken  over  some  phases  of  movement — and  are  "go- 
getters."  They  go  after  water  and  food.  By  their  sensory 
nerves  they  can  see  water  and  smell  food.    By  their  motor 



nerves  they  tell  their  skeletal  or  striped  muscles  to  go  get  it ; 
sometimes  called  the  peripheral  nervous  system.  But  non- 
striated  muscle  and  other  "vegetative"  organs  know  what  to 
do  with  air  and  water  and  food  when  brought  within  reach. 

And  if  the  air,  water,  or  food  is  bad,  they  speak  up:  a 
growl  in  the  stomach,  a  flutter  at  the  heart,  a  pain  in  the 
kidney.  When  they  speak  the  cortex  listens  in.  We  may 
not  know  what  spot  or  organ  is  speaking,  but  we  know  that 
something  has  gone  wrong. 

We  begin  to  investigate.  We  find  that  our  heart,  seem- 
ingly without  nerves,  is  singularly  well  connected  with  the 
nervous  system.  In  fact,  no  other  single  organ  in  the  body 
is  subject  to  such  nervous  control.  Wliy  not?  Its  work 
varies  with  endless  conditions.  It  knows  how  to  beat,  but 
how  is  it  to  know  when  to  speed  up  for  a  race  or  slow  down 
for  sleep?  Or  whether  to  beat  eighty  times  a  minute  for  a 
man,  or  only  seventy  times  because  it  is  working  for  a 
woman?  The  heart  must  have  accurate  and  detailed  informa- 
tion if  it  is  to  give  the  best  it  has. 

It  gets  this  information  from  two  sets  of  nerves.  One  is  the 
great  vagus  or  pneumogastric,  tenth  of  the  twelve  trunk-line 
nerves  ending  in  the  brain.  Its  messages  slow  the  heart, 
inhibit  action.  The  other  nerve  is  on  another  line,  only  indi- 
rectly connected  with  central:  it  is  an  accelerator,  speeds  up 
heart  action.  The  two  together  hold  the  heart  steady  as  a  bit 
holds  a  horse:  "gee"  means  fast,  "haw"  slow. 

A  man  looks  me  over — scornfully  as  it  were,  and  says, 
"Oh,  gee!"  The  mere  look  was  enough:  it  was  an  accelerator, 
my  heart  beats  faster.  By  what  nerve  did  that  look  or  word 
reach  my  heart,  speed  it  up,  and  slip  the  leash  on  fighting 
mechanism?  A  look  can  do  it.  One  word  can  transform  a 
man  as  pale  as  a  cool  cucumber  into  a  red-faced  fury  and 
prepare  him  to  take  on  his  weight  in  wildcats. 

A  fighting  man  or  a  weeping  woman  is  in  a  "state  of 
mind" — an  emotional  state.  Some  dogs  and  people  have 
their  "emotions"  under  control,  some  are  always  emoting. 



Emotions  are  born  of  biologic  necessity:  to  meet  the  sudden 
demands  when  we  must  run  or  fight  for  our  lives.  To  run 
or  to  fight  for  life  requires  reorganization  of  the  body.  No 
battleship  ever  carries  out  clear-decks-for-action  order  with 
the  speed  that  the  order  itself  prepares  the  bodily  mechanism 
of  the  sailors  who  hear  the  order. 

Such  co-ordinated  visceral  action  takes  place,  through  the 
autonomic  system.  "Autonomic"  because  in  control  of  activ- 
ities that  function  with  so  little  reference  to  the  higher  brain 
centers  they  seem  automatic.  It  is  not  an  independent  system 
(nothing  is,  in  the  body),  only  an  extension  of  the  peripheral, 
and  is  dominated  by  the  motor  nerves  of  the  central  nervous 
system.  It  is  a  motor  system;  it  makes  for  speedier  action 
in  the  motor  mechanism. 

The  cortex  may  be  busy  with  a  poem  under  a  tree.  The 
sight  of  a  bull  puts  cortex  out  of  action  and  switches  on  the 
autonomic  system.  As  a  result,  the  poet  can  now  break  his 
own  record  for  the  hundred-yard  dash;  or  he  can  climb  the 
tree.  The  cortex  is  still  there — if  he  can  use  it.  Prepared 
to  run  and  running  are  different  things.  Whether  he  runs 
or  climbs,  or  decides  to  wait  for  the  bull  to  make  the  next 
move,  will  depend,  among  other  things,  on  how  his  emotions 
have  been  trained,  how  his  reactions  to  fear,  rage,  pain, 
hunger,  etc.,  have  been  conditioned.  Even  a  poet  inherits 
life's  capacity  for  inhibition  as  well  as  for  excitation. 

The  great  effector  of  the  body  is  the  skeletal  muscular 
system.  With  this  the  autonomic  system  is  only  indirectly 
connected.  It  is  more  directly  connected  with  muscles  which 
control  the  pupil  of  the  eye  and  change  the  crystalline  lens; 
with  glands  in  the  mouth,  nose,  stomach,  and  pancreas;  witli 
most  of  the  arteries,  the  hair-raiser  or  goose-flesh  muscles, 
and  sweat  glands;  with  the  bladder  and  reproductive  organs. 

The  sixty-odd  ganglia  or  knots  of  neurons  in  this  system 
presumably  form  subsidiary  centers  from  which  orders  are 
relayed  from  the  central  system. 

The  fact  that  the  autonomic  system  can  be  trained  is  impor- 



tant.  It  means  that  a  reflex  mechanism  necessary  for  brutes 
can  be  educated  to  behave  as  befits  intelligence.  The  manner 
of  its  education  determines  whether  life  is  emotion  or  science. 

The  autonomic  system  is  sometimes  called  sympathetic — 
not  because  it  has  any  sympathy,  but  because  the  system 
connects  widely  distributed  activities.  What  the  system  is 
called  is  less  important  than  the  realization  that  nerves  carry 
impulses  into  and  orders  from  central,  and  that  nerves  and 
central  function  as  a  unit.  The  autonomic  nerves  are  simply 
part  of  that  organization.  It  is  not  nerves  that  go  to  school 
or  are  trained;  it  is  the  individual. 


Ever  have  cramps — in  the  sea,  a  half-mile  from  the  shore? 
It  is  bad  enough  in  bed;  sometimes  sends  you  out  on  to  the 
floor  before  the  cramped  muscle  unlocks.  In  the  water  a 
cramp  is  serious;  it  may  lead  to  panic.  Some  one  is  gen- 
erally lost  in  a  panic. 

Why  does  the  muscle  lock?  If  I  knew  I  could  rewrite  the 
history  of  civilization.  Whatever  cramps  are,  fatigue  is. 
Fatigue  is  as  yet  one  of  life's  baffling  mysteries.  Is  sleep  a 
fatigue-killer?  We  know  when  we  feel  rested  and  when  we 
are  tired.  What  is  tired?  Why  did  it  get  tired?  What  do 
we  feel  fatigued  with? 

Fatigue  is  a  physiological  process,  as  is  living,  but  it  plays 
such  an  important  part  in  all  learning  processes  and  is  such 
a  responsible  factor  in  human  behavior  that  it  must  be  talked 
about  even  though  it  cannot  be  described. 

In  a  cramped  leg  the  muscle  is  locked,  contracted.  The 
cramp  disappears  when  the  muscle  unlocks,  relaxes.  But 
contraction  is  not  the  normal  state  of  any  muscle — ^why  does 
it  lock?  Neither  is  relaxation.  Muscles  are  normally  under 
some  tension — "tonus."  This  renders  them  more  capable  of 
response  to  nerve  impulse  to  contract  or  relax.  But  why  a 
muscle,  quite  on  its  own,  as  it  were,  goes  into  a  chronic  con- 



traction,  no  one  knows.  Nor  is  it  known  why  it  often 
requires  more  time  for  relaxation  than  for  contraction. 

Muscle  works  best  under  certain  conditions.  That  at  least 
is  known.  These  conditions  include  hydrogen-ion  concentra- 
tion, temperature,  and  load.  Under  these  conditions  its 
energy  yields  more  work  and  less  heat  than  under  poor  con- 
ditions. For  example,  two  of  us  run  a  mile  in  six  minutes: 
poor  time,  but  that  lets  me  in.  At  the  end,  you  are  cool  and 
fresh  and  I  am  dripping  with  sweat.  Most  of  my  energy  went 
into  heat.  That  is  the  difference  between  the  labor  of  a 
trained  and  an  untrained  performer.  But  it  does  not  explain 
why  my  muscle  engines  got  overheated. 

Nor  why,  when  I  begin  to  tire,  my  muscles  relax  more 
and  more  slowly  in  proportion  to  the  contraction  time. 
Finally,  they  do  not  relax  at  all,  although  there  has  been  no 
change  in  the  stimulus.  This  failure  is  cramp — contracture. 
If  the  cramp  occurs  in  cold  water,  it  is  called  "cold  con- 
tracture"; does  cold  cause  the  cramp?  Otherwise,  the  cramp 
is  called  "fatigue  contracture."  Does  "fatigue"  cause  the 
swimmer's  cramp?  Do  lactic  acid,  CO2,  and  acid  phosphate 
result  from  fatigue  and  cause  contracture?  Not  in  my  legs. 
My  toes  cramp  only  when  they  are  tired  of  being  still.  That 
cannot  be  "fatigue."  The  more  I  use  them  the  less  they 
fatigue ;  nor  do  they  then  ever  cramp. 

Non-striped  muscles  of  viscera  may  possibly  have  a 
rhythmic  beat  of  their  own,  independent  of  any  action  of  the 
nervous  system.  But  skeletal  muscles  perform  under  impulse 
only  of  nerves.  All  striped  muscles  go  out  of  commission 
when  their  nerves  are  cut.  As  they  do  in  deep  sleep.  Ever 
pick  up  a  sleeping  child?  It  would  fall  apart  if  not  held 
together  by  skin  and  ligaments;  complete  relaxation  of  all 
muscles  of  the  motor  mechanism. 

Which  shows  no  "fatigue"  if  there  are  sufficient  rest  inter- 
vals between  contractions.  But  after  complete  fatigue,  at 
least  two  hours  are  required  for  recovery.  All  this  has  been 
experimentally  proved. 



But  what  is  not  cleared  up  is  why  a  repeatedly  stimulated 
muscle  steadily  loses  its  irritability,  relaxes  more  and  more 
slowly,  contracts  less  and  less,  and  finally  refuses  to  contract, 
which  fatigues  us  greatly;  or  refuses  to  relax,  and  that 
cramps  us. 

Is  it  the  nerve  ending?  Do  the  nerves  which  conduct 
impulses  to  muscles,  motor -nerves,  have  their  own  discharge 
rhythm?  The  nerve  joins  the  muscle  fiber  at  the  motor  end- 
plate.  The  poison  of  a  plant  juice  called  curare  kills  that 
plate.  A  nerve  impulse  cannot  pass  that  plate  if  there  is 
curare  in  the  system.  But  the  muscle  itself,  of  course,  is  not 
killed,  only  removed  from  nerve  impulse,  paralyzed.  From 
which  it  is  assumed  that  there  is  some  substance  at  the  motor 
end-plate  which  transmits  impulse  from  nerve  to  muscle. 
This  substance  gets  tired  or  is  made  tired  by  a  tired  muscle. 
And  whatever  fatigue  is,  or  whatever  it  is  that  causes  fatigue, 
this  substance  when  fatigued  upsets  the  all-or-none  law  of 
nerve-impulse  conduction:  the  impulse  now  passes  from  nerve 
to  muscle  with  a  decrement. 

It  must  be  so.  Muscles  are  all-or-none  performers. 
Nerves  are  all-or-none  conductors.  A  tired  muscle  is  not 
receiving  the  whole  impulse,  held  up  by  some  substance — 
which  gets  fatigued,  and  makes  us  all  tired. 

Here  is  the  point,  and  a  large  one:  living  protoplasm  balks 
at  endless  repetition.  Life  itself  is  a  response  to  change.  It 
wakes  up  at  dawn,  goes  to  bed  with  the  sun.  Sunrise  and 
sunset  are  change.  When  Johnny's  motor  mechanism  tires 
with  the  lawn-mower,  let  him  take  a  swimming  lesson;  that 
will  rest  him.  No  normal  boy  suffers  fatigue  while  swim- 
ming; although,  if  the  water  is  too  cold,  he  might  suffer  a 

Whether  fatigue  is  CO2  or  a  function  of  lactic  acid  or 
hydrogen  ions,  or  whatever  the  substance  it  affects,  the 
presence  of  fatigue  is  the  sign  of  enough.  It  is  as  though 
life  said.  Give  us  a  change.  Even  the  brainless  reflex  knee- 
kick  knows  enough  to  tire  of  repetition. 




Knowledge  of  the  human  nervous  system  is  miles  from 
complete  or  satisfactory.  Whatever  "mind"  is,  the  mind  of 
a  human  depends  on  nervous  control.  WTien  a  nerve  is  cut, 
the  mind  of  the  part  beyond  the  cut  vanishes ;  when  the  spinal 
cord  is  severed,  life  itself  vanishes,  and  with  it  the  last  trace 
of  mind — even  though  excitability  remain  a  few  hours  longer 
in  the  members. 

Living  matter  is  excitable;  that  is  its  nature.  The  nervous 
system  is  the  mechanism  through  which  excitation  is  con- 
ducted; its  nature  is  such  that  excitation  is  speeded  up  and 
is  transmitted  over  considerable  distances.  This  may  involve 
the  transport  of  electrons.  But  whether  by  this  means  or  by 
chemical  change,  the  facts  of  transmission  can  be  observed 
in  any  biological  laboratory. 

The  nervous  system  as  a  whole  has  come  to  have  what 
amounts  to  a  monopoly  of  the  excitable  nature  and  trans- 
missible quality  of  all  the  other  cells  of  our  body. 

We  may  sleep  through  a  hair-cut — so  long  as  the  hairs  are 
cut.  Let  some  be  pulled,  and  we  come  to.  Each  hair  is 
rooted  in  a  nerve;  the  nerve  cries  out  when  excited.  If  many 
are  pulled,  we  change  barbers.  WTiich  means  that  the 
nervous  system  functions  for  the  entire  organism,  knits  it 
into  one  individual.  It  is  the  mechanism  of  integration. 
Through  this  mechanism  individual  behavior,  individual 
response,  is  made  possible. 

Our  nervous  system,  then,  is  more  than  mere  mechanism 
of  adjustment  to  environment,  more  than  something  which 
has  excitation  and  transmission  capacity;  it  is  itself  the 
product  of  such  adjustments  as  have  been  made,  the  up-to- 
date  product  of  the  original  reaction  system  that  began  with 
life.  It  has  become  increasingly  complex.  That  complexity 
is  the  visible  expression  of  that  relation  to  environment  on 
which  all  individual  existence  is  founded  and  which  starts 
with  all  individual  existence. 



Our  individual  existence  starts  with  an  egg  which  responds 
to  environmental  relations.  Our  nervous  system,  at  any  one 
moment  of  our  life,  is  the  conditioned  product  of  the 
responses  that  have  been  made  up  to  that  moment.  These 
responses  have  been  made  on  behalf  of  an  individual.  This 
or  that  reaction  may  seem  only  part  response,  but  all 
responses  are  individual:  any  particular  part  response  suf- 
ficed for  the  whole  organism.  The  organism  of  billions  of 
cells  can  act  as  a  unit  because  its  nervous  system  accepts  that 

The  organism  is  the  individual — man.  The  cells  of  his 
body  live  their  individual  lives:  they  feed  and  breathe  as 
individual  cells.  But  they  are  welded  together  for  a  common 
purpose — the  unified  body  they  serve.  The  nervous  system 
permits  of  individual  action  in  that  unified  body.  It  thereby 
performs  two  groups  of  functions:  "the  physiological  adjust- 
ment of  the  body  as  a  whole  to  its  environment  and  the 
correlation  of  the  activities  of  its  organs  among  themselves; 
the  so-called  higher  functions  of  the  cerebral  cortex  related  to 
the  conscious  life." 

As  Herrick  points  out,  our  own  conscious  experience  has 
nothing  to  work  with  except  the  sensory  data  which  is  trans- 
mitted through  the  lower  brain  centers  to  the  cerebral  cortex. 
Consciousness,  then,  is  action  of  a  kind  in  the  cerebral  cortex: 
the  materials  of  consciousness  are  the  contents  of  sense, 
sensory  data. 

We  eat  and  sleep  and  snore  and  dream  and  work  and  play, 
hunt  and  fish,  get  rich  and  get  poor,  and  in  short  do  and  think 
the  usual  and  unusual  things  that  men  do  and  think.  Some- 
times we  are  conscious,  sometimes  we  are  not.  Consciousness 
is  an  organic  mode. 

Excitation  is  movement  of  ions — charges  of  electricity.  A 
tired  muscle  shows  an  increase  of  its  normal  hydrogen-ion 
concentration.  Does  this  account  for  the  failure  of  the  nerve 
to  conduct  excitation  in  extreme  fatigue?  A  nerve  conducts 
an  excitation;  time  must  elapse  before  it  can  again  be  stimu- 



lated:  about  1/lOOth  of  a  second.  During  this  interval  the 
ions  are  probably  restored  to  their  original  positions  and 
other  changes  that  occurred  reversed. 

There  comes  a  time  when  we  cannot  reverse — nor  change 
our  mind;  the  reaction-system  cannot  restore  our  equilibrium; 
the  motor  mechanism  cannot  be  relieved  of  the  waste  products 
as  rapidly  as  they  are  formed.  Stimuli  which  disturb  the 
equilibrium  of  the  physico-chemical  reactions  necessary  for 
life  cease  to  be  stimuli.  Changes  in  ion  concentrations  may 
disturb  the  equilibrium  but  no  longer  serve  as  stimuli  to 
excite  changes  necessary  to  meet  the  next  upset.  "I  will"  is 
a  fine  slogan,  but  the  kinetic  energy  which  kicks  down  doors 
and  tunnels  mountains  is  never  released  until  the  mechanism 
is  in  such  position  that  the  potential  energy  is  there.  Our 
potential  energy  is  force.  There  must  be  equilibrium  back  of 
"I  will."  Back  of  each  heartbeat  is  a  reaction  which  restores 
its  equilibrium:  it  is  always  dynamic — potential.  It  can 

With  change  to  which  we  cannot  reply,  to  which  we  can 
make  no  compensation,  death  comes  to  heartbeat  and  to  con- 
sciousness. The  protoplasm  coagulates ;  death  is  an  irreversi- 
ble change. 

The  egg  by  which  life  is  transmitted  is  a  clean  slate;  the 
record  of  change  has  been  erased.  At  birth  the  recording 
process  begins  all  over  again.  With  adult  life  most  of  the 
irreversible  changes  have  been  made;  we  have  reached 
dynamic  equilibrium. 

Do  we  do  it?  Can  we  explain  the  nature  of  our  reactions? 
Something  is  known  of  the  nature  of  water  and  many  of  its 
reactions  have  been  described,  but  none  explained.  Man  is 
not  quite  all  water.  How  much  of  the  remainder  is  hydro- 
gen ions,  catalyzers,  and  drugs,  is  not  yet  known.  Nor  is  it 
quite  known  what  fires  our  consciousness;  the  processes  of 
chemical  combustion  in  living  things  are  not  perfectly  under- 
stood. But  it  is  certain  that  all  brain  work  involves  change 
or  metabolism  in  brain  tissue.    Metabolism  in  the  nervous 



system  is  yet  to  be  worked  out  in  the  biochemist's  laboratory. 
When  it  is,  we  shall  know  more  about  memory  and  conscious- 
ness than  we  do  now.  But  enough  is  known  to  give  us  a 
working  hypothesis  and  to  rob  memory  of  some  of  its 

Neuron  metabolism  is  presumably  not  essentially  unlike 
that  of  other  reacting  protoplasms,  but  because  neurons  are 
especially  organized  for  conduction  and  are  highly  irritable, 
it  seems  reasonable  that  they  should  not  only  be  architec- 
turally unlike  other  cells,  but  should  also  be  chemically  dif- 
ferent. They  are.  In  their  neurofibrils  is  presumably  the 
substance  which  facilitates  conduction  of  impulses;  their 
chromophilic  substance  presumably  is  the  explosive  in 

The  chromophilic  substance  is  an  iron-containing  nucleo- 
protein  and  is  found  only  in  the  larger  neurons  and  dendrites, 
never  in  the  axons.  It  is  presumably  not  concerned  in  the 
general  metabolism  of  nerve  cells;  it  does  presumably  con- 
tribute to  the  rapid  liberation  of  much  energy  during  excita- 
tion. Herrick  finds  a  rough  analogy  with  fire  in  gunpowder 
and  in  a  lump  of  coal.  The  coal  burns  only  at  the  surface 
in  oxygen;  the  gunpowder,  once  brought  to  the  proper  tem- 
perature, liberates  oxygen  internally,  so  that  the  combustion 
can  take  place  simultaneously  throughout  the  mass. 

During  intense  activity  or  in  extreme  fatigue  the  chromo- 
philic substance  seems  to  disappear,  to  be  used  up ;  when  the 
neuron  is  at  rest  it  reappears.  In  a  way,  its  action  suggests 
that  of  an  enzyme.  For  the  present  it  may  be  regarded  as  a 
catalyzer  of  neuron  energy  liberation.  It  furnishes  the  kick 
back  of  brainstorms  and  the  explosive  in  flare-ups;  it  serves 
as  a  storehouse  for  the  release  of  energy  in  long-sustained 
mental  work. 

But  a  catalyzer  is  not  used  up;  no  more,  presumably,  is 
the  chromophilic  substance.  During  rest  or  inactivity  it 
reorganizes,  as  does  an  enzyme;  it  is  free  to  enter  into  a  new 
complex.    Like  enzymes,  its  action  is  both  analytic  and 



synthetic.  It  is  conceivable  that  every  action  of  the  chromo- 
philic  substance  leads  to  a  structural  change  in  the  proto- 
plasm of  the  neuron  itself.  The  neuron,  therefore,  is  not 
what  it  was  before.  It  has  learned  a  lesson;  it  will  react 
more  easily  the  next  time.  There  will  be  less  internal  resist- 
ance, as  Herrick  puts  it.  "The  change  in  the  'set'  of  the 
reacting  substance  makes  a  repetition  of  the  discharge  easier. 
It  may  be  transitory  or  long  enduring.  This  is  organic 
memory.  The  same  principle  may  work  out  in  modified  form 
in  the  cerebral  cortex  in  connection  with  conscious  memory." 

One  other  point  of  great  importance.  Theoretically,  if  not 
actually,  every  neuron  in  the  body  is  in  contact  with  every 
other  neuron  in  the  body;  but  presumably  no  one  neuron  is 
in  direct  contact  with  any  other  neuron,  at  every  junction  is 
a  synapse.  This  junction  stops  impulses  or  it  lets  them  by. 
It  is  modified  by  what  it  does;  it  is  "impressionable  to  indi- 
vidual experiences."  The  real  importance  of  this  fact  will 
appear  later.  The  point  to  be  made  here  is  that  simple 
atmospheric  vibrations  of  certain  lengths  may  strike  my  ear 
drum  and  be  conducted  by  my  auditory  nerve  as  such,  but 
when  these  vibrations  have  been  translated  by  my  cortex  and 
found  to  mean  a  word  of  five  letters  having  an  odor  like  a 
polecat,  my  entire  body  may  suddenly  be  mobilized  for 
action.  More,  I  shall  be  extremely  conscious  at  the  time  and 
a  different  man  for  the  remainder  of  my  life.  And  all 
because  the  different  protoplasms  of  my  body  are  knit 
together  by  correlation  mechanisms  of  varying  degrees  of 
complexity,  all  integrated  into  one  mechanism  which  adjusts 
me  and  with  which  I  adjust  myself. 

And  as  for  consciousness.  Sometimes  I  am  conscious, 
sometimes  I  am  not.  During  sleep  or  at  rest,  the  brain  is 
probably  in  a  state  of  dynamic  equilibrium.  Some  stimulus 
disturbs  this  equilibrium;  where  the  stimulus  ends  will 
depend  on  synaptic  resistance  and  neuron  thresholds.  If  the 
stimulus  reaches  the  cerebral  cortex,  I  shall  probably  be 



conscious  of  it — it  will  then  be  "conscious  activity,  the  kind 
of  consciousness  depending  on  the  kind  of  discharge." 

When  psychology  has  become  quite  divorced  from  psyche 
and  gets  in  bed  with  living  beings  we  shall  be  able  to  throw 
the  word  "consciousness"  into  the  discard — along  with 
"mind"  and  "memory."  Human  behavior  then  will  be  on  a 
scientific  basis  and  not  a  branch  of  literature  or  philosophic 
or  religious  speculation.  "Mind"  will  give  way  to  personal- 
ity, "consciousness"  in  general  to  specfic  exhibitions  of 
learned  behavior,  and  "memory"  to  the  calling  out  of  some 
part  of  the  individual's  striped  or  unstriped  muscle-tissue 

Do  I  remember  something?  Only  if  I  can  react  it  with  my 
manual,  verbal,  or  visceral  mechanism  as  the  case  may  be. 
Am  I  conscious?  Only  when  the  higher  brain  centers  are 
stimulated  to  activity.  Have  I  a  mind?  Well  I  am  alive — 
and  must  keep  on  making  adjustments  until  I  am  dead.  And 
that  adjustment  ends  my  personality  and  any  further  be- 
havior as  a  living  being. 

This  conception  of  a  dynamically  active  cortex  is  helpful 
in  understanding  several  phenomena  of  general  psychologic 
interest — sleep,  dreams,  consciousness,  etc.  In  sound  sleep 
it  is  presumably  in  equilibrium.  When  we  are  widest  awake, 
its  equilibrium  presumably  is  quite  upset;  changes  go  on 
until  equilibrium  is  restored. 

But  in  this  connection  Watson's  warning  against  over- 
emphasis of  the  role  of  the  nervous  system  is  useful. 

Every  sensory  structure  can,  when  stimulated,  excite  a 
segmental  reflex,  a  reflex  involving  neighboring  segments,  or 
a  reflex  involving  practically  the  whole  central  nervous  sys- 
tem. Herein  lies  the  neurological  basis  for  the  complex 
types  of  instinctive  and  habitual  reflex  acts.  Central  aff'ords 
a  system  of  connection  between  sense  organs  and  glands  and 
muscles.  Interrupt  the  connection,  the  organism  no  longer 
acts  as  whole;  some  phase  of  the  behavior  pattern  drops  out. 
But,  in  stooping  to  tie  a  shoe,  for  example,  or  jumping  in 



fright  following  a  sudden  explosion,  the  tonus  of  every 
muscle,  striped  and  unstriped,  in  the  body,  is  changed,  and 
the  glands  become  activated.  Action  takes  place  only  with 
bones,  which  means  more  food,  strain  on  the  heart,  elimina- 
tion of  waste,  etc.  While  a  simple  eye-hand  co-ordination 
brings  a  well-ordered  and  integrated  response  from  the  whole 
organism,  such  response  only  takes  place  with  central,  but 
it  can  not  take  place  without  action  in  heart,  bones,  glands, 
and  muscles. 

As  to  the  nature  of  the  processes  due  to  change  in  equi- 
librium, Herrick  assumes,  for  example,  that  the  irradiation 
of  a  nervous  discharge  into  the  visual  area  of  the  cortex 
through  the  association  tracts  will  be  determined  by  the 
existing  pathways  at  the  moment  open.  Which  pathways 
are  open  will  be  determined  by  previous  experience  (facili- 
tating transmission)  and  by  stimuli  of  other  senses,  which 
will  reinforce,  inhibit,  or  modify  the  visually  excited 
nervous  discharges,  partly  by  particular  patterns  of  memory 
vestiges  in  the  association  centers,  partly  by  temporary  states 
of  fatigue,  lassitude,  interest,  etc. — "and  it  may  be  by  count- 
less other  factors."  But,  cortical  equilibrium  having  been 
disturbed  (by  a  withering  look  or  a  trim  ankle),  cortical 
activity  will  continue  until  a  new  equilibrium  is  established — 
"by  motor  discharge,  by  fatigue  wilh  no  practical  outcome, 
by  the  fabrication  of  a  new  pattern  of  cortical  activity  or  by 
a  new  enduring  'set'  of  the  reacting  system  which  will  modify 
all  subsequent  activity  of  this  system  and  may  appear  in  con- 
sciousness as  an  idea,  a  judgment,  a  decision,  a  purpose,  or 
an  ideal." 

Consciousness  is  like  life:  there  are  criteria,  manifesta- 
tions, of  living  things;  but,  as  there  is  no  life  in  general,  so 
there  is  no  consciousness  in  general.  There  are  conscious 
modes.  The  reaction  of  ameba  to  vital  change  is  one  con- 
scious mode,  or  form  of  consciousness.  Call  it  instinct, 
impulse — what  you  will;  but  it  is  a  definite  kind  or  form  of 
energy  transformer.    In  man,  this  energy  becomes  an  object 



of  observation  because  it  influences  other  centers  of  energy 
transformation.  I  have  the  energy  to  do  several  things  at  the 
same  time — even  to  be  conscious  that  the  robins  are  greeting 
the  dawn  and  that  it  is  time  for  me  to  take  the  air.  The  fact 
of  that  consciousness  is  a  factor  in  my  behavior  and  I  adjust 
myself  accordingly.  Any  other  animal  with  my  kind  of 
adjusting  mechanism  and  with  my  experience  would  do  the 




1.  A  Stork's-eye  View  of  the  Baby.  2.  Instinctive  Behavior.  3.  Organizing 
the  Kinesthetic  Sense.  4.  The  Reflex  Basis  of  Habits.  5.  Play  and  Imitation. 
6.  The  Laws  of  Habit  Formation.  7.  Instinctive  Emergency  Behavior.  8.  The 
Fear-Hate  Organization.  9.  Childhood's  "Unconscious"  Mind.  10.  The 
Habit  of  Language.  11.  Verbalized  Organization.  12.  Adjustment  by  Thought 
and  by  Words.  13.  Learning  and  Remembering.  14.  The  Changing  Situation. 
15.  Positive  and  Negative  Adaptations.  16.  How  Habits  Are  Broken.  17.  The 
Habit  of  Sleep.  18.  "Prophecy  lies  in  ...  'I  have  dreamed.' "  19.  Learning 
to  Know.    20.  Knowing  and  Believing.    21.  The  Individuality  of  Response. 


The  stork  leaves  the  baby  and  flies  away  home.  The  baby 
knows  how  to  live;  all  it  has  to  do  now  is  to  learn  to  behave. 
It  can  learn  many  things ;  it  will  be  expected  to  learn  certain 
things.  It  is  fitted  for  life;  it  will  be  trained  to  fit  into  this  or 
that  kind  of  life.  It  has  an  inheritance;  it  will  be  asked  to 
invest  this  inheritance  in  the  coin  of  the  realm.  Its  potenti- 
alities are  unknown;  they  will  now  be  tested  and  given  rein 
to  develop  or  checked  by  the  bit  of  custom.  In  short,  every 
baby  is  born  at  a  specific  time  into  a  specific  community  witli 
definite  ways  of  living  and  set  opinions  of  those  who  do  not 
live  that  way;  to  that  life  the  baby  is  expected  to  learn  to 
adjust  itself — or,  as  it  is  sometimes  put,  to  become  an 

How  does  it  do  it? 

How  does  the  stork  know  its  way  home?  We  do  not  know. 
We  know  how  to  find  our  way  home — and  what  happens  when 
we  arrive  home  and  cannot  find  the  keyhole,  or  when  we 
promise  to  be  home  at  one  and  arrive  at  four.  Even  a  bee 
knows  its  way  home- — and  makes  for  it  in  a  "bee  line." 



Marked  terns  carried  by  Watson  in  a  hooded  cage  on  a 
steamer  from  their  nesting  grounds  off  the  coast  of  Florida 
to  Galveston,  returned  home  in  less  than  a  week  across  the 
six-hundred-mile  trackless  waters  of  the  Gulf  of  Mexico. 

Uncanny?  Only  because  we  cannot  describe  tern  behavior 
in  the  familiar  terms  of  human  psychology.  We  only  know 
that  with  this  homing  instinct  birds  get  home;  we  do  not  yet 
know  the  nature  of  the  stimulus,  whether  one  or  many,  or 
how  this  stimulus  so  excites  the  bird  that  it  makes  its 
"uncanny"  response.  But  this  we  can  say:  any  bird  born  with 
a  reaction  mechanism  that  is  not  responsive  to  life-or-death 
excitations  will  never  grow  up  to  be  proud  of  its  offspring. 

An  eel  travels  down  the  Rhine  to  the  sea,  and  keeps  right 
on  until  she  reaches  the  Azores;  lays  her  eggs;  dies.  Her 
progeny  return  to  the  Rhine.  Salmon  are  as  "uncanny"; 
from  the  sea  they  enter  fresh- water  rivers  and  ascend  far 
inland;  deposit  their  eggs;  die.  They  are  in  such  hurry  to 
make  this  journey  to  the  grave  that  they  do  not  stop  on  the 
way  to  eat.  Young  salmon  return  to  the  briny  deep  to  grow 
up,  and  find  their  way  back  up  the  very  same  river  to  pay 
their  debt  to  their  kind  and  to  their  nature. 

During  evolution,  life  has  encountered  endless  situations 
and  has  learned — sometimes  only  indifferently  well — to  meet 
these  situations  in  endless  ways.  Some  of  these  ways  are 
still  miles  beyond  us — as  Huxley  remarked  of  his  crayfish 
after  studying  it  all  his  life.  We  see  the  responses — and  too 
often  interpret  them  in  terms  of  our  own  likes  and  dislikes, 
pains  and  pleasures,  work  and  play. 

We  think  we  know  why  we  travel  a  thousand  miles  to  die  in 
the  old  home,  and  how  we  find  it.  But  why  should  a  poor  fish 
of  a  salmon  go  hungry  for  weeks,  travel  a  thousand  miles, 
breast  endless  rapids  and  climb  waterfalls,  just  to  polish  off 
life  in  the  old  home?  It  seems  stupid!  It  is:  it  has  nearly 
been  the  death  of  salmon.  Think  of  all  the  salmon  ever 
canned — all  because  they  insist  on  going  home  to  die! 

We  see  the  responses;  we  dissect  out  the  reflex  arcs  of 



nervous  mechanism  and  distinguish  receptors  from  effectors: 
the  behavior  still  baffles  us,  because  we  have  only  just  begun 
to  try  to  interpret  living  beings  as  dynamically  excitable 
organisms  with  a  capacity  to  respond  to  excitations  which  to 
them  have  life-or-death  value,  and  which  transmit  to  their 
offspring  both  excitable  structure  and  capacity  for  response. 

We  do  not  know  what  impels  salmon  to  climb  to  lakes  in 
mountains,  eels  to  cross  seas,  birds  to  migrate  halfway  round 
the  world,  amebae  to  chase  their  brothers,  or  men  to  beat  their 
wives.  We  do  not  even  know  much  about  impulses.  We  do 
know  that  some  things,  some  situations,  and  some  people, 
excite  us — sometimes  more  than  we  are  willing  to  admit  or 
is  good  for  us.   We  respond:  we  may  clean  up  or  go  broke. 

But  whatever  it  is  that  salmon,  stork,  or  ameba  responds 
to,  we  may  be  certain  that  the  response  is  an  answer  to  a 
question:  is  it  poison  or  food — shall  I  eat  it  or  leave  it  alone? 
Friend  or  foe — and  if  foe,  shall  I  run  or  fight?  And,  in 
higher  organisms,  does  she  love  me  or  does  she  not? 

These  are  the  three  big  things  in  life. 

Plants  and  animals  answer  these  questions,  each  according 
to  its  kind.  One's  poison  is  another's  food;  one's  deadliest 
enemy  is  another's  life-saver.  Each  has  its  own  specific 
reaction  system — range  of  capacity  to  act,  range  of  capacity 
to  learn.  In  short,  to  each  species  of  animals  the  world  is 
thus  and  so;  to  that  world  it  must  respond  thus  and  so;  the 
individuals  of  the  species  are  born  attuned  to  the  world  in 
which  they  must  sink  or  swim. 

The  baby  our  stork  left  is  in  the  same  boat.  Only,  if  we 
are  to  understand  it,  two  things  must  be  borne  in  mind. 

Every  species  of  higher  organisms,  both  in  plant  and  ani- 
mal world,  has  its  own  specific  life  cycle.  A  certain  cater- 
pillar eats  and  excretes  the  livelong  day  to  turn  into  a  butter- 
fly which  lays  her  eggs  while  in  the  cocoon  and  dies  before 
she  has  eaten  a  meal  or  flown  a  foot.  A  colt  dropped  to 
earth  rises  up  to  trot  off  with  its  mother.  "Infancy"  may  be 
a  minute,  it  may  be  years.    "Adult"  life  may  rise  at  sunset 



from  an  imago  in  the  water  on  the  wings  of  an  ephemera,  to 
mate,  drop  her  eggs,  and  die  before  sunrise. 

The  world  into  which  we  are  born  has  little  relation  to  the 
world  we  were  evolved  to  be  born  into:  it  is  a  man-made 
world,  full  of  whispers  and  innuendoes,  dark  corners  and 
bright  lights,  selfishness  and  greed,  stupidity  and  cruelty,  and 
many  charitable  organizations.  In  course  of  time  these 
excrescences  will  be  seen  for  what  they  are.  Then  the  years 
of  infancy  can  be  so  spent  that  the  adult  can  make  the  most  of 
his  capacity  to  mend  his  environment,  instead  of  being  so 
misspent  that  he  must  use  all  his  energy  to  fit  into  it  or  escape 
from  it. 

Eagles  have  nests,  and  coyotes  holes,  but  a  Iamb  has  no 
place  to  lay  its  head  except  alongside  mother,  and  she  must 
keep  in  touch  with  grass.  The  lamb  begins  to  jump  about 
before  it  is  a  day  old:  it  may  have  to  run  for  its  life  that  same 
day.  Having  frolicked  fleetness  of  foot  into  its  legs,  it  is 
prepared  for  the  main  business  of  life — tearing  off  grass 
between  gums  of  upper  and  teeth  of  lower  jaw. 

The  baby  the  stork  leaves  can  neither  fight  nor  run,  but 
in  its  innate  instinctive  nature  are  biologically  useful  modes 
of  response  to  the  two  big  crises  which  confront  a  human 
infant.  The  response  to  hunger  is  one.  Back  of  this 
response  is  a  mechanism  which  works  like  a  charm.  Sucking 
begins  when  the  lips  are  stimulated,  even  by  an  empty  rubber 
nipple.  Food  in  mouth  leads  to  the  next  step  in  this  reflex 
chain — swallowing.  The  reflex  chain  ends  with  the  stimulus 
of  a  full  stomach.  All  this  is  instinctive  behavior.  The  reflex 
is  the  simplest  and  most  persistent  mechanism  of  instinctive 
acts.  The  two  represent  a  primitive  response  in  a  predeter- 
mined direction. 

Nor  does  the  newborn  have  to  learn  to  "throw  up"  a  meal 
or  spit  it  out,  or  to  lick,  hiccough,  sneeze,  breathe,  or  make  a 
face — at  quinine,  for  example.  Or  draw  up  its  leg  when 
tickled.  These  reflex  responses  are  instinctive  acts,  written 
into  its  inheritance. 



In  short,  we  are  born  with  much  valuable  knowledge  picked 
up  during  the  millions  of  years  we  have  been  living;  but  we 
are  not  born  with  the  knowledge  where  food  and  water  are 
to  be  found,  or  with  a  motor  which  would  take  us  there  if 
we  knew. 

Which  means  that  our  viscera  know  how  to  live ;  our  motor 
mechanism  does  not  know  how  to  carry  the  viscera  to  the 
things  it  must  have  to  live  on.  And  we  are  infants-in-arms 
until  our  motor  mechanism  learns  to  perform  that  service  for 
us.  When  that  mechanism  learns  to  go  after  food  as  well  as 
the  viscera  know  how  to  handle  food,  we  are  going  concerns, 
we  have  some  sense.  The  first  sense  we  acquire  is  movement 
sense,  kinesthetic  organization. 


Animals  must  eat  or  die;  must  breed  or  theii^  kind  dies 
with  them.  Their  structure  and  their  nature  make  them 
responsive  to  these  two  urges  at  periods  also  determined  by 
their  nature  and  by  their  development.  It  is  also  in  their 
nature  that  their  structure  will  enable  them  throughout  their 
life  cycle  to  make  adjustment  to  vital  stimuli. 

The  higher  the  animal  life,  the  less  set  are  the  inborn 
responses,  the  more  flexible  the  adjustments.  A  monkey  is 
interested  in  more  things  than  is  a  cat  or  a  dog:  it  has  a  more 
excitable  nature.   It  learns  more  rapidly. 

The  response  mechanism  and  the  response  repertoire  will 
be  conditioned  by  the  world  the  animal  faces.  The  lion 
learns  to  jump  through  a  hoop  of  fire — a  situation  the  lion 
at  birth  did  not  confront.  A  monkey  learns  to  pick  a  lock 
or  untie  a  knot.  But  it  is  enough  for  the  monkey  at  birth  to 
know  how  to  eat  and  how  to  hang  on  to  mother:  she  will  pro- 
vide the  meals  and  carry  the  baby  along  with  her.  But  it  is 
also  necessary  that  the  baby  know  when  it  is  in  pain  and  have 
some  means  of  letting  mother  know. 

With  man,  "helpless  infancy"  reaches  its  maximum  dura- 



tion.  Whatever  instinct  is,  man  has  less  need  of  it  than  a  flea 
or  even  a  monkey.  A  monkey  at  six  knows  everything;  man 
at  six  has  just  started  to  school.  But,  like  the  monkey,  he  is 
born  with  enough  to  get  by  the  first  day. 

A  wasp  leaves  its  cell  fit  to  fly,  sting,  and  get  food.  That 
is  instinctive  behavior.  It  has  nothing  to  do  but  live ;  nothing 
to  learn  but  death.  The  human  newborn  yawns  and  looks 
about.  It  does  not  know  what  it  will  have  to  do.  Why 
instincts  when  there  are  mothers  to  teach  it  habits? 

The  mason  wasp  (mud  dauber)  is  not  so  clever  with  her 
stinger  as  is  the  saddler  with  his  awl;  she  does  not  always 
reach  the  spinal  ganglion  of  the  spider  she  stings;  she  may 
kill  it,  which  then  will  be  no  good  for  wasp's  larvae.  But  if 
she  does  reach  that  ganglion,  the  spider  is  paralyzed  and  will 
live  for  days.  She  drags  it  home,  lays  an  egg  on  it,  and  seals 
egg  and  spider  in  a  mud  tomb.  The  egg  hatches,  the  larva 
eats  the  spider,  and  digs  out,  leaving  the  empty  shell  of  the 
spider's  body  within  the  tomb.  The  wasp's  stinger  was  ready- 
made  and  her  stinging  of  spider  an  inherited  habit, 
instinctive.  The  saddler  has  to  learn  to  use  his  awl.  The 
awl  finally  functions  like  a  machine  because  innumerable 
reflex  arcs  bound  like  a  chain-gang  have  learned  to  work 
together.   The  saddler  can  then  use  his  mind  for  other  things. 

Habit  is  the  most  important  element  in  human  behavior. 
Any  animal  that  cannot  form  a  habit  must  depend  on  in- 
stinct. Instincts  make  for  routine  and  stereotyped  behavior. 
The  greater  the  capacity  to  form  new  habits,  the  wider  is  the 
possible  range  of  behavior.  This  range  in  man  is  so  great 
that  stereotyped  thought  and  action  are  evidence  of  an  ab- 
normal mind. 

Human  culture  is  back  of  human  habits.  Human  nature 
is  back  of  human  instincts.  For  example,  suppose  we  are 
about  to  enlist  or  buy  life  insurance.  Are  we  physically  fit? 
The  doctor  puts  us  in  a  chair,  asks  us  to  cross  our  legs,  and 
raps  the  patellar  ligament  just  below  the  knee.  Our  foot  flies 
out.   We  smile:  we  used  to  play  that  trick  on  each  other  when 



we  were  boys.  What  can  the  old  knee-kick  trick  have  to  do 
^sith  fitness  for  military  service  or  life  insurance?  Or  with 

Much.  The  rap  on  the  ligament  was  carried  by  a  sensory 
nerve  to  the  spinal  cord,  from  spinal  cord  by  motor  nerve  to 
the  quadriceps  femoris  muscle  (in  which  the  knee-cap  is  em- 
bedded) ending  in  the  tibia.  This  muscle  contracted;  the 
foot  kicked  out.  Spinal  cord  0.  K.  No  paresis,  locomotor 
ataxia,  or  such. 

Every  rap  on  that  ligament  is  followed  by  a  knee  jerk. 
It  is  a  reflex  act  and  implies  a  definite  reflex  arc;  such  an  arc 
exists ;  we  have  countless  such  arcs  at  birth.  It  is  not  learned 
or  acquired  or  under  control  of  the  will.  A  ray  of  light 
strikes  a  newborn's  eye :  the  eye  may  or  may  not  close,  but  the 
pupil  will  contract,  as  will  ours  under  similar  stimulus.  That 
contraction  is  a  reflex  act,  instinctive:  we  could  not  help  it. 

We  often  say,  "I  simply  couldn't  help  myself!"  It  is  the 
gospel  truth;  by  no  conscious  eff'ort  are  we  ever  complete 
master  of  ourselves.  We  may  gaze  in  open-eyed  delight  at 
a  blinding  flash  of  lightning  and  never  turn  a  hair  at  the  most 
deafening  burst  of  thunder,  but  there  is  a  limit  of  control  in 
all  human  flesh;  it  is  the  nature  of  flesh  to  be  sensitive,  of 
nerves  to  transmit  sensation. 

To  blink  at  lightning  and  jump  at  thunder  and  pull  at  the 
nipple  and  swallow  food  and  relieve  the  bladder,  etc.,  are  all 
instinctive  activities.  Because  they  are  more  complex  than 
mere  knee-kick,  pupil  contraction,  and  other  reflexes,  they 
are  called  instincts.  Instincts  are  compound  reflexes.  If  we 
could  analyze  them,  we  should  find  an  arc  for  each  of  the 
component  reflexes. 

Instinctive  behavior  is  unlearned  behavior;  it  functions 
with  the  first  adequate  stimulus;  it  is  common  to  man  and  to 
many  higher  animals;  it  is  complex;  it  is  accompanied  by  but 
not  dependent  on  consciousness;  it  is  explicit  or  implicit;  it 
is  modifiable. 

Go  to  the  ant,  sluggard !  is  no  advice  for  any  human  being. 



The  ant  is  a  slave  to  its  instincts.  It  can  only  react  in  a 
certain  way,  predetermined  at  birth,  working  on  an  inherited 
preformed  mechanism.  Requiring  no  experience,  it  gains 
none.  The  ant  is  nature's  masterpiece  of  quick  and  accurate 
uniform  behavior,  as  predetermined  as  an  oak  tree.  Its 
nervous  system  is  a  ladder;  it  must  climb  that  ladder.  Go  to 
a  monkey,  is  better  advice.  No  Primate  is  a  slave,  unless  en- 
slaved by  man.  Ants  have  been  living  the  same  life  for 
millions  of  years.  A  monkey  lives  more  in  a  year  than  all 
the  ants  have  lived  since  ants  evolved. 

Our  nervous  system  is  no  ladder;  it  is  built  around  a  tube. 
It  has  plenty  of  reflex  arcs,  but  it  is  surmounted  by  a  brain 
whose  big  business  is  to  learn  and  to  profit  by  experience. 
The  baby's  spinal  cord  is  largely  organized  at  birth,  but  its 
big  brain  is  a  clean  slate.  There  is  nothing  known  it  cannot 
learn.    With  man,  plastic  behavior  reaches  its  highest  point. 

We  do  not  inherit  instincts,  but  an  instinctive  mode  of  vege- 
tative and  reproductive  reactions;  also  an  instinctive  activity 
which  by  the  nature  of  the  stimulus  says  "yes"  or  "no,"  a 
positive  or  a  negative  response.  With  such  activity,  we  can 
learn  to  walk  and  pull  the  cat's  tail;  we  can  form  habits. 
We  bump  our  head  against  the  table;  our  next  response  to 
table  is  conditioned.  We  pull  the  wrong  cat's  tail;  our  habit 
of  response  to  cats'  tails  is  conditioned.  All  our  responses 
are  conditioned.  That  is  the  way  we  learn  to  behave.  We 
do  not  require  instincts;  we  can  acquire  habits.  If  we  get 
set  in  them,  we  can  forget  our  brains  and  live  like  ants. 

Add  it  up:  instincts  are  inherited  habits.  Have  we  more 
than  a  chimpanzee?  We  cannot  say.  But  we  can  say  that 
both  of  us  have  enough  to  start  out  in  life;  if  not,  we  are 
defective  and  do  not  go  far.  We  can  also  say  that  our  inherit- 
ance of  reflex  arcs  exceeds  that  of  the  chimpanzee  by  several 
ounces  of  neurons.  As  a  consequence,  we  have  more  nervous 
machinery  in  general,  more  neurons  to  load,  more  paths  to 
carry  the  load. 

But  the  fundamental  difference  between  man's  and  chim- 



panzee's  inheritance  is  in  parents.  Once  a  chimpanzee,  al- 
ways a  chimpanzee;  but  a  man  may  become  a  skunk  or  a 
saint.    Think  of  all  the  kinds  of  people  you  know! 

Man's  inherited  habit-to-live  can  be  modified  into  thousands 
of  ways  of  living.  We  do  not  inherit  habits  of  shaving,  wear- 
ing kimonos,  three  meals  a  day,  plug  hats,  skyscrapers,  ab- 
horrence of  pork,  four  wives,  faith  in  Sunday  schools,  or 
belief  in  higher  education  for  women.  We  do  inherit  parents 
who  do  not  want  us  to  disgrace  them  and  who  do  their  best 
to  bring  us  up  in  the  way  we  ought  to  go. 

Which  means  that  human  inheritance  varies  from  age  to 
age  and  cradle  to  cradle.  Little  the  newborn  cares  about  a 
silver  spoon  in  his  mouth — ^he  inherited  the  habit  of  respond- 
ing to  an  empty  stomach;  or  whether  the  roof  over  his  head 
is  copper  or  thatch — ^he  inherited  the  habit  of  crawling  in 
out  of  the  wet. 

To  describe  human  adjustments  in  terms  of  instincts  or 
analyze  specific  human  behavior — or  our  own  consciousness 
— into  instinctive  acts,  is  to  stir  the  mud.  Human  culture 
is  the  accumulated  responses  of  the  man-animal  to  his  man- 
made  environment.  It  accumulates,  it  varies,  because  man 
can  and  does  talk.  This  seems  a  handicap  at  times,  but  in  the 
long  run  it  has  had  enormous  consequences.  /Without  speech 
as  an  organized  tool  of  exchanging,  acquiring,  and  trans- 
mitting experiences,  human  culture  is  inconceivable. 

Life  learns.  An  ameba  probably  learns  new  tricks  not 
inherent  in  original  protoplasm.  Man  also  must  learn  by 
experience.  But  if  you  tell  me  "The  water's  cold,"  or  "That's 
a  toadstool,"  it  saves  me  time.  It  is  this  enormous  as- 
semblage of  others'  experiences  in  the  form  of  objects  and 
descriptions  which  makes  human  culture  what  it  is  and  man's 
birthright  to-day  what  it  is. 

An  engineer  will  build  an  airplane  in  less  time  than  it  took 
him  to  learn  to  drive  his  first  nail.  But  in  an  entire  lifetime 
he  could  not  alone  assemble  the  materials  for  the  airplane, 



or,  without  benefit  of  accumulated  knowledge,  learn  how  to 
make  one  nail. 

We  inherit  no  nail-driving  habit.  We  do  inherit  a  motor 
mechanism  which  feels  good  when  functioning.  We  took  our 
first  lesson  in  driving  a  nail  when  we  banged  the  rattle  on  the 
side  of  the  crib.  Later,  stimuli  of  nails,  hammer,  soft  pine, 
an  environment  holding  other  stimuli  to  activity;  countless 
reflex  arcs,  some  already  learned  in  responses  to  such  stimuli ; 
thumb  smashed,  probably!  but  the  nail  is  finally  driven. 
And  more  nails,  and  more,  until  finally  the  carpenter  drives 
nails  from  force  of  habit  like  an  instinct. 


We  learn  to  skate  in  summer  and  to  swim  in  winter,  said 
James.  He  meant  that  our  gradually  rising  curve  of  learning 
reaches  a  crest — and  stops  for  a  while.  During  summer,  we 
consolidate  all  that  we  learned  during  winter.  With  the 
next  winter,  we  start  from  a  new  level.  It  is  even  more  true 
that  we  learn  both  to  skate  and  to  swim  when  we  learn  to 
walk,  just  as  we  have  made  progress  in  learning  Chinese  when 
we  have  learned  English.  But  to  learn  Chinese,  or  to  skate, 
or  to  dance  on  our  toes,  we  must  start  early;  our  muscles 
soon  get  set  in  their  ways. 

It  is  the  first  walk  that  is  the  hardest.  The  steps  we  acquire 
later  in  life  are  mere  child's  play  compared  with  the  first  step 
the  child  learns  to  make.  Balancing  the  body  on  one  foot  on 
a  wire  rope  is  only  possible  because  we  learned  first  to  bal- 
ance the  body  on  a  ball  a  half -inch  in  diameter.  We  speak 
of  such  complex  acts  as  tennis,  typewriting,  piano  playing, 
etc.  They  are  complex,  but  the  complex  and  difficult  part 
was  learned  by  the  time  we  could  walk  across  the  room  and 
put  a  finger  in  the  cat's  eye. 

Do  we  learn  these  acts,  or  are  they  innate  responses  that 
appear  in  due  time?  We  know  that  the  newborn's  legs  are 
not  only  weak,  but  are  not  yet  shaped  for  an  upright  gait, 



and  that  its  spine  has  not  yet  taken  on  human  curves;  legs 
and  spine  grow  human.  Several  years  elapse  before  they  are 
entirely  human  in  character.  But  they  are  human  enough  to 
walk  on  within  twelve  or  fifteen  months. 

The  response  to  the  first  pin-prick  is  not  the  simple  reflex 
of  hand  going  to  the  spot  that  is  injured.  Rather:  random, 
aimless,  uncontrolled,  uncoordinated,  unadjusted  movements 
of  body,  arms,  legs.  Possibly  driving  the  pin  in  deeper.  Con- 
trast these  vain  random  motor-mechanism  movements  with 
the  prompt  and  coordinated  pattern-reaction  to  pain  or  nox- 
ious stimulus;  or  that  of  visceral  and  glandular  systems  to 
pain  of  pin-prick  or  to  any  pain  or  to  any  stimulus  which  the 
little  mite  of  protoplasm  interprets  as  deadly. 

It  may  seem  much  more  important  that  the  infant  should 
know  where  and  how  to  put  its  hand  on  that  pin  than  it  is  to 
get  so  upset  it  loses  its  appetite — and  possibly  its  dinner. 
And  the  madder  it  gets,  the  less  likely  it  is  to  find  the  pin. 
But  man  was  not  evolved  in  a  thorn  tree,  nor  were  there  pins 
when  the  human  adjustment  system  was  perfected.  Nor  has 
man  yet  progressed  to  the  point  where  he  is  born  adapted  to 
"all  the  comforts  of  a  home"  and  the  tenseness  of  civiliza- 
tion. We  have  to  learn  to  walk  and  to  train  our  hands  and 
fingers  in  such  space  and  to  such  keys  as  our  fate  allots  us. 

Random  and  uncoordinated  movements  represent  the  range 
of  our  motor  mechanism  inheritance  at  birth;  except,  of 
course,  the  grasping  reflex.  That  comes  with  us.  Many  new- 
borns can  support  their  body  by  either  hand;  by  a  hand  so 
tiny  and  by  an  arm  so  frail  that  it  does  not  appear  strong 
enough — and  does  not  know  enough — to  support  a  half -pint 

Swimming  is  not  an  inheritance.  The  newborn  is  afraid  of 
water,  and  if  introduced  to  it  under  painful  circumstances 
may  carry  the  fear  for  life. 

The  earliest  body  movements  are  chiefly  of  an  avoiding 
nature.  A  three-days-old  infant's  nose  was  lightly  pinched. 
It  began  to  strike  out  with  its  hand.    In  eighteen  seconds  tlie 



hand  found  its  mark:  it  struck  the  experimenter's  hand.  On 
the  second  trial  it  found  his  hand  in  two  seconds.  By  the 
fourth  day  the  infant's  hand  had  learned  its  lesson:  it  could 
at  once  strike  the  experimenter's  hand. 

The  newborn  can  turn  its  eyes  toward  the  light.  Not  until 
days  later  can  it  fix  its  eyes  on  a  light  or  move  them  with  a 
moving  light.  It  will  reach  out  for  a  lighted  candle.  But 
only  after  150  or  more  trials  has  it  learned  to  direct  its  hand 
to  the  flame.  A  few  trials  suffice  for  the  infant's  hand  to 
avoid  the  flame.  The  more  flame  the  hand  discovers,  the  less 
the  hand  tries  to  discover.  For  "flame"  substitute  "stick 
of  candy." 

These  early  months  lead  to  simple  eye-hand  co-ordinations. 
But  only  after  long  and  repeated  experiment  can  the  little 
hand  or  finger  be  directed  to  the  spot  which  stim^ulates  the 
eye.  So  with  body  and  leg  movements.  Their  actions  become 
definite  and  sharp  only  after  months  of  trial  and  error.  Mean- 
while the  entire  motor-machinery  grows  in  size  and  in  strength. 

Every  movement  that  comes  under  control  is  a  movement 
learned,  useful  in  the  next  adjustment  movement.  Muscles, 
tendons,  ligaments,  become  coordinated.  Thus  habits  of 
motion  and  movement  are  formed.  A  few  years  later  these 
will  be  put  to  use  in  making  pies  or  playing  marbles,  or 
shooting  a  rifle,  or  chopping  w^ood. 

Hundreds  of  muscles.  What  can  they  not  learn  to  do? 
But  in  all  this  learning  countless  little  habits  are  formed: 
habits  because  learned.  A  time  comes  when  the  youngster 
can  pick  up  a  glass  of  water  from  the  table  and  carry  it  to 
his  mouth;  over  one  hundred  muscles  involved.  Each  per- 
forms at  the  right  time,  does  just  the  needed  work  and  no 
more.  The  levers  involved!  The  wonderful  coordination! 
No  machine  works  so  perfectly  as  the  body  machine  can. 

The  great,  the  essential,  the  refined,  the  delicate  move- 
ments are  learned  within  three  years.  That  little  mechanism 
grows  up  with  us.   Throughout  life  we  call  upon  it  to  run,  to 



swim,  to  climb,  to  dance,  to  jump,  to  "hold  'em,"  to  "knock 
'em  stiff." 

Movements  and  motions  of  the  body  mechanism  can  be 
learned  because  muscles,  tendons,  and  joint  surfaces  are 
themselves  sources  of  impulses:  receptors,  sense  organs. 
Our  brain  can  thereby  organize  our  body.  We  walk  along 
new  gravel  beds,  plowed  fields,  dusty  roads,  sandy  beaches, 
or  city  pavements,  without  stumbling  or  missing  a  step.  We 
kick  a  cat,  but  not  a  brick.  Nor  a  hat  on  April  first:  we 
kicked  that  hat  once — it  had  a  brick  under  it.  We  learned. 
By  experience  we  learn  to  walk  through  plowed  fields,  through 
grass,  ashes,  leaves.  Training,  learning,  habits  of  the  motor 

With  this  kinesthetic  organization  we  sense  hard  stone,  soft 
grass,  heavy  lead,  the  resistance  of  water,  bushes,  walls.  If 
we  learn  to  sleep  on  a  feather  bed,  a  hair  mattress  is  as 
"hard  as  a  board."  The  city-bred  boy  stumbles  all  over  a 
farm:  his  kinesthetic  sense  has  something  to  learn.  Water 
looks  soft:  it  feels  as  hard  as  rock  if  we  dive  in  flat.  Only 
by  experience  do  we  learn  whether  it  is  safe  to  jump  from 
a  height  upon  a  pile  of  leaves  or  a  load  of  hay.  By  falling 
off  a  bicycle  we  learn  enough  to  stay  on. 

This  kinesthetic  organization  is  of  enormous  importance. 
It  carries  us  through  life  if  we  have  built  it  up  well,  giving 
us  time  to  choose.  The  individual  who  is  always  stubbing  his 
toe,  spraining  his  ankle,  stumbling  over  others'  feet,  running 
into  doors  and  sharp  corners,  falling  downstairs,  picking  up 
hot  pokers,  barking  his  shins,  and  "didn't  know  it  was  so 
far"  or  "so  high"  or  "so  hard"  or  "so  deep"  or  "so  steep"  or 
"so  slippery,"  has  poorly  developed  kinesthetic  sense:  he  is 
inexperienced  in  movement  or  without  a  full  complement  of 
kinesthetic  habits. 

The  motor  mechanism  starts  to  school  the  day  the  baby 
is  born.  And  every  mother  knows  that  it  is  "not  still  a  min- 
ute." Within  thirty  months  it  has  fallen  down  a  thousand 
times;  walked  or  backed  or  bumped  into  everything  avail- 



able;  handled  everything  greasy,  sticky,  smooth,  rough,  hot, 
cold,  dry,  wet,  hard  and  soft,  within  reach.  Falls  out  of 
crib  and  chair  again  and  again.  Finally  learns  to  climb  in 
and  out.  Bumps  its  nose,  its  head,  its  shins;  gets  its  fingers 
caught  in  doors.  Learns  that  it  can  slide  down  the  banisters 
and  the  cellar  door  and  climb  up  a  rope  but  not  a  lace  curtain. 

Very  busy  months  these.  There  are  not  enough  words  to 
describe  all  the  motor  habits  a  healthy  youngster  learns  within 
thirty  months. 

The  kinesthetic  sense  only  gets  into  consciousness  when 
something  goes  wrong.  With  our  motor  mechanism  we  swim 
along,  unconscious  of  the  unending  and  beautifully  coordi- 
nated movements  of  bony  levers  worked  by  myriads  of  micro- 
scopic muscle  engines.  Then,  without  warning,  cramps!  We 
are  suddenly  conscious  of  our  body  machine.  Pain  anywhere 
in  muscles,  joints,  tendons,  ligaments,  brings  our  body 
machine  home  to  us. 


Practice  makes  perfect.  Even  a  car  "drives"  better  after 
the  first  thousand  miles.  And  as  for  the  driver  himself!  At 
the  end  of  the  first  day  he  ever  drove  a  car  he  was  a  wreck. 
For  two  reasons. 

Fear  lest  he  wreck  the  car:  too  emotional.  He  suffered 
enough  in  anticipation  to  lose  a  dozen  cars,  several  legs,  ribs, 
eyes,  lives.  Other  fears  under  his  belt  moved  him  deeply: 
was  it  safe,  any  possibility  of  its  blowing  up,  would  the  gas 
hold  out,  etc.?  He  did  not  know  his  car;  it  was  a  great  un- 
known; the  unknown  is  always  a  threat.  He  did  not  know  his 
road,  nor  its  manners  and  its  customs,  its  curves  and  its 
grades.  The  new  way  is  always  a  threat :  what  is  around  the 

The  other  reason.  His  own  motor  mechanism  was  tired 
all  over.  Throughout  the  day  his  muscles  had  been  tense, 
taut  as  fiddle  strings,  keyed  up  for  emergency  action.  His 



eyes  saw  too  much,  his  ears  heard  too  much,  and  his  nose  was 
on  the  qui  vive  for  hot  boxes,  burning  rubber,  scorched 
grease.  His  control  over  his  car's  brakes  and  gears  was 
better  than  over  his  own.  It  was  as  though  he  were  running 
his  body  on  high  with  the  emergency  brakes  on.  More  than 
that:  his  hands  and  feet  had  not  learned  to  coordinate.  To 
do  one  thing  with  one  foot  and  quite  a  different  thing  with  the 
other,  steer  with  one  hand  and  work  a  brake  or  gear-shift  with 
the  other,  is  a  learned  operation.  He  had  not  yet  learned  it. 
He  could  do  it,  but  at  an  awful  price. 

Now  he  drives  three  hundred  miles  a  day;  is  as  fresh  as  a 
daisy;  has  a  good  time,  sees  the  country,  talks  his  hat  off, 
smokes  a  dozen  cigars.  Does  not  give  his  car  a  thought  the 
whole  day.    He  is  as  automatic  as  his  engine. 

Same  car,  same  road,  same  driver.  And  the  same  process 
in  every  act  of  learning,  beginning  with  the  act  of  standing 
up  or  the  first  walk  in  life.  We  have  time  for  the  high  spots 
in  life  if  we  have  learned  how  to  cross  the  routine  valleys 
by  force  of  habit. 

Watch  a  small  boy  at  his  first  copybook.  Face  screwed  up 
in  a  knot,  brow  furrowed,  mouth  open,  tongue  out,  one  fist 
clutching  the  desk,  the  other  the  pencil,  legs  tied  up  tight. 
Every  muscle  in  that  boy's  body  is  engaged  in  learning  to 
write.  Finally  he  learns  to  write  with  one  arm,  and  can 
smile  and  wink  and  let  his  legs  go  to  sleep.  But  when  we  go 
to  the  theater  we  help  kill  the  villain  and  embrace  the  heroine: 
we  sigh,  we  groan,  we  clench  our  fists. 

Do  you  know  which  stocking  you  put  on  first  this  morning 
or  which  trousers'  leg  you  filled  first?  Do  you  recall  how  you 
felt  the  first  time  you  ever  wore  a  dress  suit,  or  how  long  it 
took  you  to  put  it  on,  or  to  learn  to  tie  a  bowknot?  Can  you 
bathe,  shave,  and  dress  in  six  minutes?  I  can  do  it  in  less 
than  five. 

A  skilled  performer  at  the  piano  or  typewriter  or  on  the 
tennis  court  acts  like  an  automaton.  But  no  mere  automaton 
— ^human  or  otherwise — ever  makes  a  great  performer. 



For  this  reason:  heightened  sensitivity  of  the  central 
nervous  system  increases  the  response  of  the  reflex  arcs.  A 
tap  on  flexed  patellar  tendon  elicits  no  kick  when  one  is 
asleep.  Sleep  means  that  central  has  hung  up.  But  try  out 
the  knee-kick  with  your  teeth  clenched  or  your  fist  tightly 
doubled  up:  more  kick.  Get  real  mad:  more  kick.  A  lad 
of  sixteen  is  given  a  little  instrument  squeezed  in  the  hand  to 
measure  muscle  strength.  He  squeezes:  so  many  pounds. 
"Best  you  can  do?"  "The  best."  His  best  girl  enters  the 
room.  He  now  beats  his  record  by  several  pounds.  Central 
nervous  system  more  active;  everything  more  active,  except 

A  good  habit  is  a  well  learned  habit  put  to  useful  purpose. 

The  competent  driver  guides  his  car  as  a  clever  boy  his 
bicycle:  the  right  muscles  work  to  the  right  amounts  at  the 
proper  time  and  in  proper  order.  A  car  or  a  curve  or  a  hole 
or  a  honk  ahead  is  stimulus  enough  for  eye  or  ear;  the  ad- 
justment is  made  as  though  it  were  a  reflex,  as  easy  as  pie. 
It  is  an  acquired  reflex.  Paths  have  been  worn  for  such 
highly  complex  responses  as  driving  an  auto,  an  airplane,  a 
tennis  ball,  a  pair  of  chopsticks,  knife  and  fork. 

All  our  habits  act  by  force  of  habit  because  these  paths  are 
worn.  We  awake  in  the  morning  and  "before  we  know  it" 
we  are  at  the  breakfast  table,  or  possibly  "come  to"  only 
when  some  headline  in  the  paper  catches  our  eye — perhaps 
already  half  through  our  breakfast.  And  yet,  before  we 
"came  to,"  we  went  through  a  thousand  acts:  dressing,  shav- 
ing, etc.,  etc.,  some  of  them  really  complex  performances 
requiring  delicate  adjustments.  And  the  whole  bag  of  tricks 
performed  as  a  result  of  a  single  stimulus:  a  bell,  a  call,  a 
ray  of  sunlight,  gastric  tetanus,  what  not.  After  that  one 
stimulus  one  act  followed  another:  as  Paine's  "Fall  of  Pom- 
peii" followed  from  one  match. 

Yet  there  were  a  thousand  responses  available  for  that 
breakfast  stimulus.  The  stimulus  was  not  necessarily  fol- 
lowed by  a  yawn,  a  stretch,  push  covers  down,  one  leg  out, 



other  leg  out,  slippers,  etc.,  etc.,  etc. — one  conditioned  reflex 
touching  off  another.  But  that  chain  of  reactions  had  been 
performed  so  many  times  that  the  paths  connecting  up  these 
countless  reflexes  had  been  worn ;  all  the  other  possible  paths 
of  response  off'ered  more  resistance  because  they  had  not  been 
worn  by  constant  action. 

A  habit,  then,  is  an  act  so  often  repeated  that  it  runs  itself : 
it  does  not  need  our  conscious  attention;  we  can  give  our 
attention  to  something  else. 

The  dropped  colt  picks  itself  up  and  walks  off":  walking 
reflex  paths  all  ready  for  use;  he  does  not  have  to  learn  a 
thing  about  walking.  Think  of  the  ways  a  child  can  learn  to 
walk,  and  with  only  half  as  many  legs  as  a  colt!  But  whether 
the  child  learns  to  walk  goosestep,  Spanish,  or  in  Chinese  size- 
minus-four,  depends  on  incidence  of  parents  and  accident 
of  locality — for  each  insists  that  its  own  style  is  right.  Nearly 
all  our  early  steps  are  conditioned  into  habits  backed  up  by: 
"Walk  like  I  walk  or  I'll  ..." 

The  average  mortal  has  only  one  habit.  The  one  stimulus 
which  rouses  him  from  sleep  carries  him  through  the  day 
and  back  to  bed  and  to  sleep.  All  days  look  alike  to  him. 
Saturday  night  is  also  conditioned  into  the  chain:  no  fresh 
stimulus  needed  for  the  bath!  His  body's  clock  is  likewise 
set  for  Sunday.  That  day,  too,  goes  by  according  to  schedule, 
and  when  done  is  itself  the  stimulus  to  resume  a  new  week. 
One  habit  after  another,  like  a  chain,  functioning  as  one. 
Works  like  a  clock  wound  up  for  life.  Makes  a  perfect 
clerk,  "hand,"  or  maid. 

This  one-habit  mode  of  existence  is  fine;  it  gives  the  brain 
a  complete  rest.  The  possessor  need  never  have  a  thought! 
He  is  a  skilled  performer,  but  never  great,  on  piccolo,  at 
lathe,  behind  counter,  or  on  a  stool.  He  does  not  even  make 
a  good  soldier.  There  must  be  visceral  dynamics — generally 
called  "guts" — behind  a  bayonet  charge;  and  high-strung 
central — called  "brains" — in  control  for  a  sharpshooter. 



The  difference  between  action  in  an  automatic  machine  and  in 
a  human  genius  is  brains. 


I  smile  when  you  tickle  me;  I  cannot  help  it,  it  is  a  reflex. 
If  you  smile  back,  I  will  learn  to  smile  when  you  smile.  The 
drive  in  life  is  hunger.  The  action  in  life  is  to  secure  food 
and  mates  to  satisfy  hunger.  Play  is  preliminary  action — 
trying  out,  testing  the  capacity  of  range  of  action.  It  differs 
from  the  reactions  of  adult  life  in  that  it  lacks  the  consum- 
mation response  or  adjustment.  The  action  has  no  ulterior 

Play  is  not  an  instinct;  nor  is  it  unique  in  human  beings  or 
identical  in  the  human  race.  It  is  a  form  of  acquired  be- 
havior. The  games  I  play  as  child  or  adult  will  be  con- 
ditioned by  my  bents  and  especially  by  social  environment. 
What  is  played,  who  plays  it,  how  it  is  played,  all  depend  on 
learned  habits  of  individual  response  and  can  only  be  inter- 
preted in  terms  of  situation,  stimulus,  and  response. 

The  stimulus  back  of  play — whether  of  puppies,  children, 
or  adults — is  a  motor  mechanism  which  was  built  for  action, 
glows  with  action,  and  in  childhood  grows  best  by  action. 

Weeding  the  garden  or  picking  potato  bugs  is  action.  But 
there  are  drawbacks.  Repetition — same  stimulus,  same  re- 
sponse ;  and  no  end  in  sight — there  seem  to  be  so  many  weeds, 
so  many  bugs ;  if  they  are  to  be  cleared  out,  the  pace  must  be 
kept  up.  That  means  that  the  impulse  to  respond  to  other 
stimuli  that  may  rise  and  do  keep  rising  up  to  beckon  the 
child  aside  must  be  repressed. 

Play  is  generally  actions  of  several  kinds  at  the  same  time. 
Even  in  a  game  of  marbles  a  half-dozen  different  activities 
may  function  together.  The  difference  between  marbles  and 
professional  baseball  is  chiefly  years:  the  men  have  their 
game  better  organized;  are  better  players  because  more 
habituated  to  it;  and  stick  closer  to  their  game.    But  some- 



times  their  game  becomes  lost  in  a  fight  with  words,  catcalls, 
and  pop  bottles. 

Margie  making  mud  pies  and  mother  making  apple  pies 
further  illustrate  the  difference  between  play  of  children  and 
of  adults  and  between  play  and  work.  Mother's  work  ends 
when  the  pie  leaves  the  oven.  Margie  may  grow  stale  over 
her  pie  before  she  has  made  one,  or  she  may  go  right  on 
making  pies  until  she  uses  up  all  the  mud.  Her  impulse  is  for 
action  rather  than  for  consummation.  She  will  stop  when  the 
impulse  for  mud-pie  action  is  replaced  by  another  with  more 
pull.    Such  as:  "Let's  play  dolls,"  or,  "Dinner  is  ready." 

Impulse  to  action;  gratification  of  that  impulse;  hang  the 
consequences :  of  such  is  the  play  of  children,  the  daydreams 
and  castles-in-Spain  of  adults. 

It  is  of  little  consequence  to  Margie  if  her  pie  is  dough  or 
too  big  or  too  little  for  her  pie  pan.  And  of  less  consequence 
to  Johnny  when  as  Heap  Big  Injun  he  "scalps"  Margie  with  a 
celluloid  paper  cutter.  And  if  Margie  plays  the  game  she 
will  pretend  to  be  scalped,  catch  her  "blood"  in  her  apron, 
and  fall  down  "dead." 

What  man  tied  to  his  job  all  day  does  not  yearn  now  and 
then  to  be  a  Dick  Deadeye,  a  Jesse  James,  or  a  Captain  Kidd! 
Boys  can  be.  They  rob,  they  hold  up  trains,  they  capture 
ships,  they  bury  and  dig  up  chests  of  gold.  We  come  from  a 
long  line  of  freebooters.  There  is  nothing  in  our  inheritance 
which  savors  of  factory,  treadmill,  or  office  stool.  We  must 
acquire  these  priceless  habits,  and  often  at  the  loss  of  our 
entire  original  inheritance,  which  included  freedom  to  fight 
or  run,  and  everlastingly  to  fool  around. 

The  sheer  joy  of  being  alive,  the  supreme  joy  of  action  in 
the  child!  Watch  a  four-year-old  work  off  his  surplus  steam. 
Not  only  is  every  muscle  of  his  body  in  action,  but  his  face 
and  his  speech  box  are  at  work.  It  is  as  though  his  entire 
being  were  so  sensitive  to  excitation  that  the  slightest  wind 
that  blows  excites  him  to  new  effort. 

W^y  not?  He  has  only  just  discovered  the  most  wonderful, 



the  most  excitable,  the  most  insatiable  mechanism  in  the 
world:  a  growing  human  being,  himself!  That  mechanism 
discovered,  the  boy  or  girl  now  sets  out  to  discover  the  world, 
and  does  easier  than  later  in  life.  Life's  innate  curiosity  has 
not  yet  been  crushed;  nor  has  imagination,  the  capacity  to 
make  believe,  yet  been  killed  by  the  "realities"  that  grown- 
ups cling  to  like  shipwrecked  mariners  to  a  rotting  spar  in 

Spontaneous.  As  all  life  is,  outside  hoopskirts  and  boiled 
shirts.  Impulsive.  Where  does  the  impulse  come  from? 
Where  does  every  living  impulse  come  from — ^without  or 
within?  Both.  Living  beings  are  expressions  of  the  relation- 
ship between  conditions  that  invite  life  and  beings  that  re- 
spond to  these  conditions.  And  back  of  the  gratification  of 
food  and  mate  hunger  and  the  decision  to  fight  or  flee  is 
knowledge,  information,  trying  things  out.  Testing  oneself, 
learning  one's  own  capacity. 

Play  is  the  beginnings  of  knowledge.  Banging  the  rattle 
on  the  crib  or  getting  a  toe  in  one's  mouth  is  an  early  lesson 
in  wisdom. 

Which  means  that  there  is  no  sharp  line  between  playing 
Jesse  James  and  being  Jesse  James.  But  the  child  who  stops 
with  a  stick  for  a  gun  will  bring  down  no  bigger  game  in 
later  years  than  he  can  kill  with  a  daydream.  Those  of  us 
who  live  only  in  hopes  build  only  castles  in  our  own  air. 

The  practical  application  is  this:  two  boys  will  pick  more 
than  twice  as  many  potato  bugs  as  one  and  pick  them  faster  if 
a  definite  goal  is  set — a  quart,  or  a  quarter.  Still  better  re- 
sults can  be  had  by  setting  a  phonograph  near  by  with  a  good 
rhythmic  swing  to  it — say,  the  "Sambre  et  Meuse"  or  the 
"Washington  Post  March."  Life  hates  monotony,  but  loves 
rhythm;  in  heartbeat,  in  intestinal  contraction,  in  canoeing, 
in  poetry,  in  music. 

But  do  not  expect  the  child  to  be  like  you  through  mere 
imitation.  The  child  will  smile  when  smiled  at,  laugh  when 
others  laugh,  yell  when  others  yell,  look  at  what  others  are 



looking  at,  listen  when  others  listen,  run  with  or  after  or  from 
others,  and  duck  when  others  duck.  One  sheep  over  the  fence, 
all  over.  Not  a  sound  at  night :  one  dog  barks ;  in  five  minutes 
fifty  dogs  are  yelping.  We  also  applaud,  hiss,  whistle,  yawn, 
light  up,  with  the  crowd.  Stimulus  and  response.  Your 
lighting  up  is  stimulus  for  the  same  reaction  on  my  part. 

There  is  also  a  more  direct  conditioned  stimulus.  I  cut 
my  finger:  it  bleeds,  it  hurts;  I  wince.  You  cut  your  finger: 
I  see  blood,  I  wince.  Watch  the  crowd  at  a  prize-fight.  They 
duck,  they  dodge,  they  "Ouch!"  They  are  only  less  affected 
by  the  blows  than  the  receivers,  or  only  less  jubilant  than 
the  man  who  delivered  them.  There  is  much  human  nature 
on  exhibition  at  the  prize  ring  and  swimming  hole. 


Without  habits  we  are  in  a  bad  way,  as  poorly  equipped 
for  life  as  though  we  had  surrendered  to  habits — then  we  are 
in  a  bad  way.  The  clock  striking  twelve  may  be  adequate 
stimulus  for  me  to  remove  my  clothes.  If  I  cannot  control 
that  stimulus,  the  authorities  will:  the  clock  strikes  that  hour 
twice  a  day. 

This  is  an  extreme  case,  but  it  will  serve.  The  clock  strikes 
twelve :  bedtime.  But  noon  is  not  midnight.  The  mere  strike 
of  twelve  is  not  an  adequate  stimulus.  My  bodily  mechanism 
is  not  in  the  habit  of  running  down  at  the  noon  hour. 

If  noon  is  my  hour  for  food,  the  stroke  of  twelve  sets  off 
a  different  mechanism.  If  my  noon  behavior  is  routine  and 
well  learned,  habit  will  carry  me  through.  I  close  my  book, 
adjust  my  desk,  reach  for  my  hat  and  coat,  etc.,  etc.  By 
one  o'clock  I  am  back  at  my  desk.  Habit  carried  me  through 
the  hour.    My  conscious  activity  was  planning  a  vacation. 

During  that  lunch  hour  I  performed  hundreds  of  individual 
acts,  one  after  another,  in  regular  order;  constituting  a  fairly 
distinct  routine  or  habit  of  behavior.  Although  my  mind  was 
busy  with  fishing  tackle,  canoes,  and  such  things,  /  did  not 



have  to  look  out  for  lamp-posts,  breaks  in  the  pavement,  or 
step-downs  at  the  curb.  I  had  learned  to  thread  crowded 
streets,  remove  my  hat  on  entering  a  restaurant,  eat  with  a 
knife,  pay  the  meal  check,  etc.  All  habitual  performances: 
learned  responses,  acquired  reflexes,  habits.  Otherwise,  the 
one  hour  allotted  for  my  meal  would  not  have  sufficed.  One 
unlearned  in  city  streets  might  spend  a  half -hour  crossing 
Times  Square;  if  unaccustomed  to  a  menu,  much  time  in  de- 
ciding what  to  order. 

We  begin  with  no  acquired  habits;  we  begin  at  once  to 
acquire  them;  with  these,  to  acquire  others.  But  when  we 
get  to  be  mere  bundles  of  habits,  when  we  knoiv,  when  our 
mind  is  made  up,  when  nothing  can  move  us,  we  are  through; 
we  have  used  up  all  the  blank  pages  we  inherited  on  which  to 
write  our  life. 

People  do  get  that  way.  They  lose  capacity  for  new  expe- 
rience, ability  to  form  new  habits,  plasticity  for  new  modes 
of  response  to  change.  "Life  is  not  what  it  used  to  be."  In 
reality,  they  cannot  respond  to  change.  The  cab-driver  who 
cannot  learn  to  drive  a  car  is  out  of  luck.  Whole  groups 
find  themselves  in  midair  because  they  cannot  change  their 
habits  fast  enough  to  keep  pace  with  change.  Their  emotional 
reaction  is  wasted,  misspent  energy.  They  do  not  thereby 
change  conditions,  nor  are  they  themselves  thereby  adapted. 

The  champion  golfer  is  not  thinking  about  his  stroke:  he 
knows  his  golf:  it  is  a  habit.  He  is  thinking  about  the  Cup, 
or  his  Girl.  If  he  had  to  think  out  each  stroke,  he  could  not 
even  qualify.  Ask  him  to  describe  any  one  particular  shot 
after  the  game :  he  probably  will  not  even  be  able  to  recall  it. 

"A  centipede  was  happy  'til 
One  day  a  toad  in  fun 
Said,  Tray,  which  leg  moves  which?' 
This  raised  her  doubts  to  such  a  pitch 
She  fell  exhausted  in  the  ditch, 
Not  knowing  how  to  run." 



Habit  formation — golf,  tennis,  pitching  hay,  eating 
spaghetti,  chewing  tobacco,  going  to  church — is  at  bottom  like 
any  other  form  of  learning.  Learning  to  play  the  piano  or 
checkers,  to  read  Greek  or  talk  Choctaw,  to  solve  puzzles  or 
problems  in  higher  mathematics,  involves  no  new  principles 
not  used  in  learning  to  walk  or  in  forming  the  habit  of  rush- 
ing to  the  window  every  time  the  fire  engine  snorts  by. 

Most  men  shave  themselves,  but  go  to  the  barber  shop  for 
a  hair-cut.  It  was  not  always  thus,  nor  is  it  thus  in  all  lands. 
Custom.  Custom  also  is  habit.  Our  repertoire  of  habits  is 
conditioned  by  the  company  we  keep.  It  is  not  immoral  to 
eat  with  a  knife,  or  a  vice  to  drink  tea  from  a  saucer;  but 
men  are  socially  executed  for  less. 

Take  shaving.  I  move  from  Fiji  to  Main  Street  with  a 
normal  face  of  hair.  Decide  to  shave  in  sheer  self-defense. 
Do  not  like  the  idea — emotionally  wrought  up.  Two  things 
follow:  I  am  not  likely  to  forget  that  shave;  if  I  am  not  too 
excited  I  will  be  able  to  give  it  the  best  I  have.  Law  number 
one  of  learning:  emotional  reinforcement;  the  reflex  arcs  are 
keyed  up  for  new  experience.  I  may  so  dislike  the  idea  of 
shaving  that  my  emotion  takes  a  real  fighting  mood;  the  re- 
flex arcs  are  keyed  up  to  resist. 

Not  having  the  shaving  habit  or  habituated  to  razor-sharp- 
ness, I  cut  myself.  More  emotion.  Never  will  forget  that 
shave.  Nor  am  I  likely  to  forget  the  move  which  resulted  in 
a  cut.  Second  law :  attention  or  vividness.  Learning  to  shave 
is  learning  to  confine  the  razor  edge  to  the  surface  of  the 
face.  Old  school  of  hard  knocks.  If  the  cut  were  serious, 
my  learning  to  shave  might  end  with  the  first  lesson.  Many 
boys  stop  with  one  lesson  on  a  pipe. 

Cut  not  serious.  And  it  is  finally  all  off".  Shave  again  next 
day.  Much  easier  this  time.  Suppose  I  had  waited  a  montli: 
less  easy;  too  much  time  to  forget  what  I  had  learned  well 
enough  to  remember  a  short  time.  Memory  of  first  shave 
and  memory  of  movements  made  are  difl'erent  processes: 



different  reflex  arcs  involved.  Third  law:  recency.  No  one 
learns  to  play  the  fiddle  with  one  lesson  a  week. 

The  fourth  law  follows — keep  it  up:  repetition.  Practice 
makes  perfect,  wears  paths  through  the  nervous  system. 

I  may  begin  this  first  shave  at  the  age  of  forty.  I  have  had 
no  opportunity  in  life  to  form  habits  of  action  on  a  reflected 
image,  nor  have  I  formed  habits  of  using  hands  for  more 
delicate  operations  than  digging  yams.  I  try  a  half-dozen 
times.  My  face  is  a  sight!  I  give  it  up — as  many  men  do; 
it  is  hard  to  teach  an  old  dog  tricks.  That  is  why  the  boy  beats 
his  father  at  golf.  Law  five:  every  man  has  his  limit.  But 
with  enough  stimulus  the  limit  can  be  extended.  If  the  father 
had  to  beat  his  son  or  have  his  allowance  cut  off",  he  would 
be  more  likely  to  succeed. 


Every  living  being  has  an  inborn  emergency  equipment. 
For  countless  beings  the  equipment  is  inadequate;  they  go 
down  like  flies  before  new  foes,  new  diseases,  new  situations. 
A  large  percentage  of  all  the  human  beings  ever  born  died 
before  maturity;  the  emergency  may  have  been  a  rusty  nail, 
a  venturesome  spirit,  a  backward  disposition.  Anything 
which  threatens  life  or  disturbs  its  peace  of  mind  or  upsets  the 
system  is  an  emergency. 

Emergencies  cannot  be  listed ;  they  are  too  numerous.  Nor 
can  they  be  described  in  general  terms ;  they  are  individually 
discreet.  Half  a  loaf  is  always  better  than  no  bread,  but 
there  are  times  when  a  half -loaf  is  the  dynamic  equivalent  of 
a  human  life,  when  half  a  minute  spells  victory  or  defeat,  or 
life  or  death.  There  are  few  of  us  whose  life  at  one  time  or 
another  has  not  hung  by  a  thread. 

What  do  we  do,  what  is  our  response  to  crisis?  Fight  or 
flee?  It  depends.  The  cry  of  "Women  first!"  on  the  Titanic 
was  enough  to  keep  the  men  from  fighting  for  the  boats:  life 
was  not  worth  fighting  for  when  the  loser  was  a  woman.  Nor 



worth  saving  when  a  spar  would  only  support  one:  a  man  let 
go  of  a  spar  that  a  woman  might  live!  This  is  human  be- 
havior at  its  highest.  Possible  because  our  inborn  emergency 
equipment  can  be  trained,  conditioned,  educated,  made  to 
obey  the  orders  of  our  head.  But  it  is  so  well  organized  and 
so  powerful  that  few  can  turn  its  command  over  to  the  cortex, 
fewer  still  who  can  conquer  it.  Greater  is  he  who  conquereth 
self  than  he  who  taketh  seven  cities! 

Greater,  because  self-preservation  is  the  first  law  of  nature ; 
and  the  higher  we  climb  in  nature's  scale,  the  better  organized 
life  becomes  for  self-preservation.  Man  has  more  means  at 
his  command  for  self-preservation  than  any  other  animal, 
largely  because  he  has  more  ways  of  destroying  his  enemies. 
Cities  and  the  "taking  of  cities"  arose  in  response  to  man's 
desire  to  anticipate  emergencies. 

The  difference  between  self-preservation  and  self-control 
is  the  difference  between  all  gorillas  and  some  men.  If  man 
used  only  his  inborn  emergency  equipment  in  a  fight  with  a 
gorilla,  he  would  lose — or  die  of  fright  before  the  gorilla 
could  lay  hands  on  him.  Fighting  instinct,  yes;  and  fleeing 
instinct  also.  But  a  worm  will  turn.  A  rat  will  run  for  its 
life;  cornered  or  caught  by  a  leg  in  a  trap,  it  will  fight  for 
its  life. 

There  is  another  kind  of  response,  the  kind  we  keep  on 
making  during  our  unconquered-self  lives.  We  are  dress- 
ing, already  late  for  dinner.  We  break  a  shoestring;  we  can- 
not find  a  certain  shirt  stud;  and  then  that  crowning  insult,  we 
drop  the  collar  button  and  it  rolls  under  the  bureau.  Now 
we  are  mad.  We  roar  like  a  caged  lion;  we  say  words,  stamp 
the  floor,  kick  a  chair,  yank  out  the  bureau.  Battles  have 
been  lost  on  account  of  such  trifles. 

What  happened?  Almost  everything.  Upset — literally. 
Lost  his  head :  that  is  true  also.  Also  lost  his  appetite.  The 
wife  is  so  disgusted  she  loses  her  temper — and  calls  him 

It  is  a  brute  reaction.    It  is  a  biologic  reaction:  it  requires 



neither  learning  nor  headpiece.  Out  of  our  inborn  emer- 
gency equipment  we  build  up  our  attitudes,  fight  windmills 
and  straw  men,  and  rip  and  roar  up  and  down  the  world,  or 
tremble  like  a  leaf  at  every  breath. 

I  saw  the  commander  of  a  United  States  warship  run  like 
mad  four  blocks  to  prevent  a  black  cat  crossing  his  path. 
That,  to  him,  meant  certain  death.  Such  fears  are  norms  of 
behavior;  they  furnish  countless  impulses  for  action.  An- 
other commander  might  also  have  been  moved  by  the  fear  of 
black-cat-calamity,  but  more  moved  by  his  uniform  to  die  in 
his  tracks  rather  than  run  four  blocks  to  head  off  death. 

To  be  moved  though  we  move  not,  is  no  mere  figure  of 
speech.  Some  movements  we  can  control,  if  we  have  learned 
control;  but  not  the  visceral  mechanism  which  tells  motor 
mechanism  to  move,  nor  adrenin  which  prepares  the  whole 
body  for  action. 

Even  a  cat  prepares  for  action.  It  assumes  a  fighting  pos- 
ture, lashes  its  tail,  and  spits.  Man  has  no  tail  to  lash  and 
when  he  is  mad  or  scared  cannot  spit  because  his  salivary 
glands  are  out  of  action;  but  his  internal  responses  to  emotion 
are  as  real  as  the  cat's;  the  visceral  organization  retires  in 
order  that  the  motor  mechanism  can  have  all  of  the  body's 
energy  available.  When  we  are  so  mad  we  cannot  eat,  the 
viscera  say:  "All  right,  we  are  not  asking  you  to  eat;  kill 
somebody,  or  move." 

"Every  little  movement  has  a  meaning  of  its  own,"  as  the 
old  song  declared;  it  is  also  true  that  every  movement  moves 
something.  We  are  never  more  physiologically  correct  than 
when  w^e  say,  "That  moves  me."  Between  birth  and  death 
many  are  "moved"  enough  to  dig  a  Panama  Canal,  yet  they 
never  move  themselves  up  out  of  the  cellar  of  life. 

The  difference  between  being  moved  to  disgust  at  the  sight 
of  a  dead  cat  and  moving  to  remove  the  cat  is  one  of  life's 
little  jokes  that  make  human  life  so  interesting. 

We  are  moved  with  unstriped  or  visceral  muscle.  We  move 
with  striped  or  skeletal  muscles.    To  make  a  gesture  is  to 



make  an  excuse  for  moving.  We  are  moved  with  less  effort 
than  we  move:  our  unstriped  muscles  function  without  the 
cortex.  They  run  themselves,  and  if  we  are  not  in  charge  they 
run  us.  In  mobs  and  panics  they  run  riot.  Every  emotion — 
anger,  love,  merriment,  jealousy,  grief,  fear,  remorse — is  an 
implicit  bodily  movement. 

Emotions  vary,  in  individuals,  communities,  nations,  races; 
are  under  different  degrees  of  control;  are  aroused  by  vary- 
ing situations.  Emotions  are  older  than  the  human  race;  but 
outside  the  human  race  are  put  to  no  such  sublime  or  ridicu- 
lous ends.  We  do  not  begin  life  with  specific  loves,  hates, 
and  fears.  Some  can  go  through  life  without  set  hates  and 
loves.  They  can  look  people  and  things  over  and  decide 
whether  they  are  worth  loving  or  hating,  and  if  they  are, 
possess  them  or  do  their  best  to  clear  the  earth  of  them.  But 
as  we  are,  not  one  in  ten  can  love  a  Hindu  or  a  Jap  or  the 
other  political  party.  And  much  of  thinking  and  talking  is 
in  terms  of  hates  and  fears  and  loves.  We  murder  at  least 
something,  if  not  somebody,  every  day.  And  love — there  are 
quite  as  many  things  to  be  loved  as  people.  In  fact,  there 
'is  nothing,  it  seems,  that  cannot  come  within  range  of  our 
love,  except  our  enemies.  Yet  there  are  those  who  "hate  the 
whole  .  .  .  sex";  that  means  half  the  human  race. 

Is  it  in  our  very  nature  to  hate  our  enemies,  impossible  to 
love  them?  Why  is  the  very  cornerstone  of  Christ's  teachings 
so  rarely  taken  literally?  James  thinks  those  "swayed  by  it 
might  well  seem  superhuman  beings.  Their  life  would  be 
morally  discrete  from  the  lives  of  other  men,  and  there  is  no 
saying  what  the  effects  might  be:  they  might  conceivably  trans- 
form the  world." 

They  might  indeed. 

As  the  world  is,  hate  is  given  freer  rein.  Recently  it 
reigned;  and  each  half  of  the  world  besought  the  same  God 
to  help  it  kill  the  other  half.  We  can  hate  enough  to  kill,  but 
killing  no  longer  solves  problems,  nor  hating  an  enemy  con- 
vert one. 



Fear  is  old  stufif,  out  of  date.  It  should  be  thrown  off  with 
our  swaddling  clothes.  And  yet  it  probably  plays  a  greater 
part  than  hope  in  the  daily  lives  of  most  men  and  women. 
Fears  are  played  upon  by  all  sorts  of  propagandists  for  politi- 
cal, social,  and  religious  purposes.  Fear  of  hell-fire  is  sup- 
posed to  lead  to  love  of  heaven;  fear  of  "ign'runt  foreigners" 
to  hatred  of  aliens  and  so  to  the  closing  of  the  doors.  And 
the  only  reason  this  nation  could  not  be  led  to  hate  Germany 
as  France  did  was  because  we  could  not  be  made  to  feel  the 
fear  of  Germany  as  France  did. 

But  for  most  of  us  life  is  only  meat  and  the  body  raiment. 
Same  reaction  system,  same  environment:  stereotyped  be- 
havior because  our  world  stands  still.  And  an  enormously 
valuable  emotional  reservoir  of  energy,  capable  of  moving 
mountains  and  giving  all  life  a  joy-ride,  is  expended  in  hating 
those  we  envy  and  kicking  against  the  pricks  or  in  fleeing  in 
terror  from  our  shadows  because  we  cannot  shake  them  off. 

And  so  it  is  that  an  instinctive  emotional  endowment  rooted 
deep  in  the  body  of  life  and  inherent  in  man  and  mammals 
and  all  living  beings  that  meet  dangerous  situations  with  com- 
plex mechanisms  which  must  function  as  a  unit  and  without 
warning,  becomes  personal  and  individual.  The  organiza- 
tion of  that  endowment  into  specific  fears  and  hates  and  gen- 
eral attitudes  favoring  negative  and  positive  responses  begins 
the  day  we  are  born. 


"When  I  was  a  child,  I  spake  as  a  child.  I  understood  as 
a  child,  I  thought  as  a  child :  but  when  I  became  a  man,  I  put 
away  childish  things."  Some  childish  things  we  do  put  away, 
and  we  do  forget  most  of  the  rag  dolls,  tin  soldiers,  and  mud 
pies;  but  we  get  our  start  in  childhood  for  much  of  our  bent 
and  most  of  our  set.  We  do  not  put  away  our  nature.  Paul 
was  an  exception. 

We  are  afraid  of  the  dark,  of  little  green  worms,  of  hun- 



dreds  of  things.  And  get  emotionally  excited  about  them. 
Some  react  to  a  cabbage  worm  as  they  would  to  a  wild  ele- 
phant or  to  a  mouse;  and  are  as  nearly  scared  to  death  as 
life  lets  them.  It  is  no  merit  of  their  own  that  they  have  not 
died  of  fright  a  thousand  times. 

We  are  not  born  that  way.  The  newborn  sets  up  a  fear 
reaction  only  to  fearful  stimuli:  the  bang  of  a  door,  being 
dropped,  a  sudden  push  or  pull  at  its  blanket;  especially  by 
removing  its  support.  It  catches  its  breath,  clutches  at  any- 
thing within  reach,  closes  its  eyes,  cries,  voids  waste.  Memo- 
ries of  life  in  the  trees?  Why  not:  sudden  noises  and  move- 
ments and  withdrawal  of  support  were  real  dangers  then. 
The  infant  could  not  flee,  but  it  could  be  scared;  later  it  runs 
and  hides  when  it  is  afraid. 

A  rat  learns  to  thread  a  maze  for  food:  it  must  pass  a 
trap  which  always  terrifies  it.  Remove  the  trap:  it  jumps 
as  though  the  trap  were  present.  A  dog  chases  a  cat  up  a  tree 
four  times  a  day.  Every  time  the  dog  appears  I  appear.  By 
and  by  the  cat  takes  to  the  tree  without  the  dog — my  face  is 
enough  to  make  it  climb  a  tree. 

A  small  dog  was  tossed  into  the  carriage  of  a  180-days-old 
child.  The  sudden  and  unexpected  move  terrified  it.  A  year 
later  it  showed  the  same  kind  of  terror  at  tame  white  mice. 
A  door  was  slammed  and  at  the  same  time  a  cat  was  shown  to 
a  child;  thereafter  it  was  afraid  of  the  cat. 

The  child  is  afraid  of  a  sudden  and  loud  noise.  It  hears 
the  thunder,  sees  the  lightning;  it  learns  to  be  afraid  of  the 
lightning.  If  the  flash  is  blinding,  it  is  afraid  of  the  room. 
If  there  is  some  particular  person  in  the  room  every  time  the 
lightning  flashes,  the  child  learns  to  be  afraid  of  that  person, 
lightning  or  no  lightning. 

With  a  what-not  loaded  with  what  not  in  the  parlor  and  a 
dresser  covered  with  hand-painted  junk  in  the  spare  bedroom, 
and  both  parlor  and  bedroom  in  perpetual  gloom,  means  must 
be  found  to  keep  little  Willie  out.  A  short-cut  is  found  in 
the  fact  that  Willie  can  be  scared.   And  Willie  is  scared.  By 



the  time  he  is  three,  or  sooner,  he  is  as  big  a  coward  as  his 
mother  was  when  she  was  three.  He  is  afraid  of  the  dark; 
jumps  every  time  a  door  is  slammed;  squeals  at  the  sight  of 
a  mouse;  and  if  a  bat  flies  into  the  room,  the  whole  house- 
hold is  in  a  panic.  And  everybody  has  bad  dreams.  And 
little  Willie  comes  out  of  his  nightmare  in  a  cold  sweat  with 
a  scream:  some  ghost  story  has  done  its  work. 

We  move  about  in  a  lighted  room  with  the  aid  of  our  eyes. 
In  a  dark  room  we  are  not  distracted  by  what  we  see  and  con- 
sequently are  more  alert  to  what  we  feel  and  hear.  We  keep 
meeting  with  the  unexpected,  sometimes  the  sudden — crash  of 
a  falling  chair,  bark  of  a  dog,  bump  on  the  forehead.  And 
by  the  time  our  fear  of  the  dark  has  become  further  condi- 
tioned by  ghosts  and  hobgoblins,  we  are  more  than  afraid  of 
a  dark  graveyard.  And  if  mother  is  afraid  of  strangers  and 
shows  it,  we  are  afraid  also,  because  our  habit  of  expectancy 
of  her  behavior  is  dislocated. 

So  with  rage.  The  baby  cannot  fight,  but  by  cries,  slash- 
ings with  arms  and  legs,  stiffening  of  body,  flushed  face, 
clenched  fists,  and  held  breath,  it  shows  its  rage  when  its 
nose  is  pinched,  head  held,  or  its  body  hampered.  And  it 
soon  acquires  the  ability  to  kick  and  slash  and  scream.  I 
have  seen  a  boy  of  two  beat  his  head  on  the  floor  in  a  rage  at 
being  denied  something.  Such  early  outbursts  are  signs  of 
the  coward  and  the  murderer  that  are  in  us.  The  way  these 
potentialities  are  trained  is  the  key  to  character  and  the  clue 
to  most  of  our  attitudes. 

A  nurse  bathes  a  child  each  day,  first  tickling  its  feet  or 
pinching  its  nose.  A  habit  grows  up,  functioning  like  an  in- 
stinct on  reflex  arcs.  The  mere  sight  of  the  nurse  calls  out 
a  gurgle  or  a  rage.  If  the  nurse  wears  a  blue  dress  habitually, 
the  blue  dress  is  enough.  If  the  baby  knows  only  one  blue 
dress  and  that  blue  dress  always  means  tickle  or  pinch,  any 
blue  dress  becomes  enough  for  gurgle  or  a  fit. 

We  come  to  hate  everything  associated  with  our  early  hates; 
afraid  of  everything  associated  with  early  fears.    The  ran- 



dom  fears  and  rages  come  to  be  attached  to  new  objects  not 
contemplated  in  the  original  scheme  of  kill-or-cure  emotional 
reinforcement.  They  become  specific.  The  baby  is  not 
naturally  afraid  of  lightning;  it  is  afraid  of  a  sudden  crash. 
Nor  is  it  naturally  afraid  of  darkness,  snakes,  strangers, 
graveyards,  or  black  cats. 

Our  emotions  are  conditioned  in  the  same  nursery  in  which 
our  growing  body  learns  its  first  steps.  As  the  movements  of 
motor  mechanism  become  habits  and  so  function  on  smooth- 
running  reflex  arcs,  the  emotions  themselves  become  organ- 
ized: the  live-or-die  glands  and  the  autonomic  nerves  learn 
special  modes  of  behavior.  They  take  on  habits,  learn  new 
responses,  acquire  new  friends,  new  foes,  new  fears.  The 
mouth  waters  under  certain  conditions.  Fear  is  called  out 
under  certain  conditions.  Certain  persons,  things,  situa- 
tions, call  out  tantrums,  cries,  rages;  others  are  sources  of 
attachment,  loves. 

Practice  makes  perfect — ^hates  and  fears  as  well  as  tennis- 
players  and  card  sharps.  One  does  not  naturally  love  a  cat 
or  hate  a  nurse  or  fear  a  mouse.  But  with  practice  the  thresh- 
old is  lowered,  the  message  gets  a  quicker  response.  Only 
intense  stimuli  at  first  called  out  these  emotional  responses. 
But  a  youngster  "nearly  scared  to  death"  is  already  on  the 
way  to  be  a  coward.  The  child  "nearly  tormented  to  death" 
has  laid  the  foundation  for  a  vicious  temper. 

It  is  like  a  cork.  First  time  out  requires  eff'ort.  There- 
after, any  old  corkscrew  will  suffice.  By  and  by,  a  thumb- 

The  function  of  emotion  is  quick  action  and  a  long  memory. 
If  I  am  the  victim  of  a  $100  counterfeit  bill  to  oblige  a 
stranger  who  needs  change,  I  am  not  likely  to  oblige  the 
next  stranger  requiring  change.  I  might  even  "take  it  out 
on  him."  We  do  such  things.  The  horse-buyer  knows  that 
a  horse  which  has  had  the  mange  does  not  forget  it:  it  is  tied 
in.  He  strokes  the  flank  of  a  prospective  purchase.  Lip 
quivers :  that  horse  had  the  mange. 



Love,  fear,  and  hate  start  out  together;  they  grow  up  to- 
gether. Meanwhile,  the  reflex  which  enables  the  newborn  to 
support  its  body  by  its  hands  soon  disappears;  the  human 
mother  does  not  hang  her  baby  on  a  limb  to  dry,  nor  does  the 
infant  have  to  cling  to  her  while  she  climbs  down  a  tree.  It 
disappears  from  lack  of  use.  The  primitive  hate  and  fear 
types  of  behavior  would  also  disappear  if  they  were  not  at 
once  set  to  work. 

The  adjusting  mechanism  learns — only  too  blindly.  Until 
we  ourselves  are  blind.  Having  eyes,  we  see  not  what  there 
is  but  what  we  think  we  see.  We  see  with  a  body  that  by 
nature  has  a  huge  capacity  to  hate  that  which  threatens  us, 
to  fear  that  which  endangers  us,  to  love  that  which  protects 
and  feeds  and  tickles  us.  Our  ancestors  had  to  have  a  fear- 
response  to  the  new,  the  unexpected,  the  sudden,  and  the 
strange.  That  is  no  reason  why  we  should  jump,  turn  pale, 
sweat,  gasp  for  breath,  close  our  eyes  and  open  our  mouths, 
and  feel  creepy  every  time  we  hear  thunder  or  backfire,  or 
are  left  alone  in  the  dark,  or  confront  a  novel  and  strange 
idea.  Nor  should  the  same  emotion  that  makes  us  fear  the 
novel  and  the  strange  impel  us  to  hate  reason — even  though 
reason  interfere  with  our  routine  behavior,  including  atti- 
tudes, desires,  ideals,  ambitions,  and  loves.  We  do  not  get 
jealous  of  reason  or  want  to  fight  it;  but  we  do  get  so  enraged 
at  a  book  that  we  throw  it  in  the  fire,  so  mad  at  an  opinion  that 
we  would  like  to  crucify  the  man  who  expresses  it. 

The  haunting  fear  in  Dickens's  day  seems  to  have  been 
poverty;  the  supreme  dread,  the  almshouse.  What  is  our 
haunting  fear,  our  supreme  dread?  Have  we  progressed 
very  far? 

With  "pep"  we  can  make  decisions,  use  our  heads;  but 
when  the  visceral  nerves  take  charge,  decisions  are  made  for 
us — we  are  as  human  as  iron  filings  around  a  magnet  or 
famished  hogs  around  a  swill  barrel.  A  man  in  a  "towering 
rage"  is  more  physically  fit  for  murder  than  one  in  cold 
blood — that  is  what  a  towering  rage  is  for,  prepare  the  body 



for  action  with  adrenin.  Hate  is  biologically  useful.  Do 
we  save  it  up  for  the  hateful  occasions  and  get  the  work  out 
of  it  it  can  do,  or  squander  it  right  and  left? 

Fear  and  rage  are  twins:  born  of  the  same  necessity.  But 
we  are  born  of  human  parents  in  a  state  of  civilization.  Civi- 
lization clings  to  savagery  and  brutality  because  fundamental 
emotional  states  are  retained  as  weapons  in  the  endless  battles 
of  religion,  society,  and  nationality.  Biologic  fears,  hates, 
and  loves  are  put  to  a  thousand  uses  that  could  never  have 
been  contemplated  in  the  original  scheme  of  evolution.  That 
scheme  says :  if  your  neighbor's  eye  offend  you,  pluck  it  out ; 
but  that  scheme  made  no  provision  for  theft,  swindling,  ly- 
ing, blackmail,  slavery,  war.    Our  scheme  does. 

Our  bottled  emotions  find  curious  outlets:  giggles,  tears, 
laughter,  shame,  remorse,  rage,  grief,  love,  fear,  as  the  case 
may  be ;  and  take  us  to  fights,  dances,  games,  theater,  specula- 
tion, futile  argument,  Monte  Carlo,  or  the  Count  of  Monte 
Cristo;  or  they  may  end  in  hysteria,  phobias,  manias. 

The  big  question  for  each  one  of  us  individually  is  whether 
our  acquired  repertoire  of  specific  loves,  fears,  and  hates  will 
suffice  to  keep  us  on  good  terms  with  ourselves  and  at  peace 
with  the  world.  Many  a  man  loses  his  job  because  his  viscera 
have  never  been  educated  nor  his  emotions  trained.  Note  too 
that  under  stress  of  strong  rage  or  fear  activity  in  the  digestive 
system  closes  down,  predisposing  to  intestinal  disorders  in- 
cluding bacterial  toxins  and  consequently  to  other  far-reach- 
ing organic  changes.  Love  on  the  contrary  hastens  food 
digestion  and  heightens  metabolism.  Love  is  a  better  tonic 
than  rage  or  fear. 


Look  at  a  thirty-months-old  boy;  better  yet,  mind  him  for  a 
few  days!  You  are  looking  at  Freud's  Unconscious  Mind, 
Watson's  Unverbalized  Behavior. 

Why  can  we  recall  nothing  of  those  first  thirty  months, 



most  of  us  nothing  of  the  first  forty  months?  Enough  hap- 
pened. If  all  our  bumps,  knocks,  cuffs,  and  "repressions" 
are  locked  up  in  the  Unconscious,  it  is  a  spacious  place. 

What  became  of  all  the  food  our  blood  absorbed  during 
those  months?  Some  was  built  into  our  bodies,  some  was 
used  as  energy,  and  what  was  left  over  was  stored  as  fat. 
What  happened  to  the  Don'ts,  Naughty-naughtys,  and  Shame- 
on-you's?  Some  got  built  in  as  parts  of  habits  of  response. 
We  learned  to  love  our  mother,  nurse,  anybody  or  anything 
that  got  conditioned  into  our  response  mechanism  for  loving. 
We  learned  likewise  to  hate  tlie  butcher  boy  who  pulled  our 
ear  or  pinched  us  every  chance  he  got;  and  forever  after 
disliked  everybody  who  suggested  butcher  boy.  Butcher  boys 
should  be  more  careful. 

Horses  also. 

A  young  man  is  upset  by  the  sight  of  a  horse  and  will  cross 
the  street  to  get  away  from  one.  This  is  "strange,"  we  say.  It 
is  a  "psychosis,"  says  Freud;  and  by  analysis  of  the  Uncon- 
scious can  be  cured.  It  is  next  to  nothing,  says  the  psycholo- 
gist; all  of  us  have  our  little  peculiarities:  some  of  us  are 
delighted  at  the  sight  of  a  horse  and  will  cross  the  street  to 
pat  it  or  kiss  it  on  the  nose.  Further,  says  the  psychologist, 
I  know  when  I  am  conscious  and  that  "consciousness"  is 
simply  being  conscious;  and  that  I  know  nothing  that  I  cannot 
name  or  describe.  Abnormal  behavior  toward  a  horse  or 
anything  else  seems  mysterious  only  because  we  are  not  in 
possession  of  all  the  facts  or  even  principal  factors  back  of 
the  behavior  of  the  individual. 

The  horse  that  bit  the  child  made  him  dislike  all  horses. 
He  cannot  now  recall  the  bite;  his  reaction-system  can  and 
does.  In  one  lesson  he  learned  to  mistrust  a  horse.  Many 
big  things  are  learned  early  in  life  with  one  lesson.  Few 
pick  up  a  red-hot  poker  or  stick  their  tongues  to  an  ice-cold  bit 
of  iron  twice.   One  lesson  was  enough :  it  took  the  skin  off. 

I  have  no  memory  of  my  red-hot-poker  lesson,  but  I  have  a 
scar  on  my  hand;  I  can  recall  to  memory  the  skin  of  my 



tongue  I  left  on  the  ice-cold  iron  I  was  invited  to  "taste," 
although  it  left  no  scar  on  my  tongue.  One  incident  happened 
when  I  was  two;  the  other,  when  I  was  six.  We  have  no 
memory  for  our  early  kinesthetic  and  emotional  organization 
— the  Freudian  Unconscious, 

The  story  of  an  elephant  balking  at  a  bridge  where  he  had 
had  a  mishap  seventeen  years  earlier,  although  the  bridge  was 
now  concrete,  may  or  may  not  be  true.  The  point  is  that  if 
I  have  an  unconscious  mind,  the  elephant  has.  Also  dogs, 
goldfish  and  oysters.  Every  animal  has  a  dynamic  mechanism 
that  can  be  shocked  at  one  shock  and  profit  by  experience. 

Which  means:  we  can  all  learn  and  what  we  learn  makes 
us  what  we  are — and  determines  whether  we  want  more  of 
it  or  not.  Our  bodies  learn  thousands  of  things  we  cannot 
describe  or  name.  We  have  a  thousand  likes  and  dislikes 
for  which  we  can  give  no  explanation  beyond:  "I  just  like  it," 
or,  "I  simply  can't  bear  it!" 

We  remember  back  to  a  certain  fairly  definite  period  of 
our  lives ;  beyond  that  our  conscious  memory  is  a  solid  blank, 
yet  our  body  acts  as  though  it  remembered.  It  does,  but  that 
is  not  memory;  not  by  such  remembering  are  we  conscious. 
If  so,  there  would  be  no  excuse  to  postulate  Unconscious. 

It  is  behavior — no  doubt  about  that.  Call  it  unverbalized. 
The  unverbalized  in  us  is  all  that  the  body  learned  before 
our  babblings  were  organized  into  speech :  modes  of  response 
learned  without  words.  We  cannot  think  about  it  because 
thinking  is  talking  without  perceptible  movement  in  speech 
mechanism.  We  cannot  be  conscious  of  it — as  conscious 
is  used  in  psychology,  the  "act  of  naming  our  universe  of 
objects  both  inside  and  out" — because  we  cannot  connect  it 
up  with  the  mechanism  by  which  we  name  our  universe  of 
objects.  For  the  same  reason,  we  cannot  remember  it.  Nor 
will  any  amount  of  psycho-analysis  bring  it  into  memory. 
Often  it  can  be  brought  to  light  with  outside  help — mothers, 
nurses,  etc. 

Before  we  take  on  habits  of  speech  we  take  on  a  huge 



amount  of  habits  of  mind:  kinesthetic  and  emotional  organi- 
zation. Innumerable  actions  are  performed  with  the  skeletal 
muscles  so  often  that  they  function  like  inherent  reflexes. 
So  also  innumerable  mental  attitudes — prejudices  for  and 
against  all  manner  of  people  and  objects — are  called  out  so 
often  that  the  body-mind  instinctively  reacts.  The  visceral 
muscles  and  the  entire  autonomic  system  "work  like  a  charm." 
These  early  conditioned  habits  have  enormous  influence  on  the 
future  of  the  individual. 

Watson  contrasts  the  child  of  four  just  home  from  the 
movies,  who  talks  you  deaf,  dumb,  and  blind,  with  a  child  of 
twenty-seven  months  who  is  a  skillful  performer  on  a  large 
kiddy-car.  He  could  guide  it,  coast  downhill,  and  make  all 
the  adjustments.  His  kinesthetic  organization  was  complete 
master  of  the  car.  But  "Billy  ride  kiddy-car"  was  his  only 
parallel  word  organization.  Which  means  that  Billy  has  no 
memory  organization  of  these  bodily  processes  except  when 
he  is  so  placed  that  he  can  exhibit  the  bodily  organization. 

Billy  had  been  a  bottle  baby.  At  the  age  of  twenty-seven 
months  he  was  tested  as  to  his  memory  for  a  bottle.  At  the 
regular  hour  he  was  told,  "Dinner  ready,"  and  put  in  a  crib 
and  handed  a  bottle,  as  was  the  custom  fifteen  months  before. 
Billy  reacted  like  a  tramp  who  asks  for  pie  and  is  given  an  ax 
— ^he  got  mad.  Dinner?  In  a  crib  with  a  bottle  of  milk? 
Crib  meant  nothing  to  him.  He  had  never  learned  to  be 
afraid  of  it;  he  had  forgotten  it.  The  crib  habit  was  gone, 
buried  beneath  other  habits.  Bottle  also.  "Dinner"  to  him 
was  meat  and  vegetables.  When  the  nurse  said,  "Take  your 
milk,"  Billy  began  to  chew  the  nipple —  thought  it  was  a  new 
kind  of  meat!  And  he  looked  at  his  mother  with  disgust  for 
cheating  him  out  of  his  dinner. 

The  entire  crib-bottle-nipple-sucking-smiling  habit  was 
gone.  Neither  objects,  faces,  nor  words  used  when  Billy  was 
a  bottle  baby  could  now  call  out  any  of  the  old  habit  re- 
sponses. Adults  often  choke  when  they  try  to  suck  through  a 
straw :  it  has  been  so  long  since  they  used  that  inherent  habit. 



Infancy  is  infancy,  the  next  stage  after  fetal  life.  Dur- 
ing infancy  we  prepare  to  shift  for  ourselves.  That  is  the 
biologic  significance  of  infancy.  It  is  no  more  unnatural  or 
unconscious  than  fetal  life.  We  learn,  take  on,  acquire, 
habits  of  behavior. 

We  may  form  incestuous  attachments:  have  an  (Edipus  or 
an  Electra  complex.  But  such  attachments  are  not  talked 
about,  because,  as  Watson  says,  "society  is  not  organized  to 
ban  incestuous  attachments  in  the  making";  there  were  no 
repressions.  Habits  connected  with  "the  slowing  or  speeding 
of  the  sexual  organs"  have  not  been  verbally  organized.  Few 
men  and  fewer  women  have  paralleled  their  sex  organization 
with  words. 

Most  of  our  emotional  organization,  from  infancy  to  old 
age,  is  never  verbalized.  There  are  neither  adequate  words 
nor  social  mechanism  for  word  conditioning  of  the  infant. 
Elimination,  eructation,  releasing  gas,  masturbation,  etc., 
were  verbalized  only  when  exhibited  in  the  presence  of  others. 
In  short,  nearly  all  visceral  and  emotional  habits  are  as  a  rule 
learned  without  parallel  verbal  organization.  They  make  up 
our  unverbalized  behavior. 


An  Egyptian  king  wanted  to  learn  the  original  language, 
possibly  the  speech  of  the  builders  of  the  Tower  of  Babel  be- 
fore their  language  was  confounded.  He  had  some  children 
brought  up  by  deaf  mutes.  The  children  learned  the  deaf- 
mute  language.  There  was  no  more  an  original  language 
than  an  original  bill  of  fare  or  an  original  wardrobe. 

The  bullfrog's  spouse  call  has  probably  changed  little  since 
the  first  frog,  impelled  by  love  and  with  the  aid  of  vocal 
cords,  lifted  up  his  voice.  If  there  is  an  "original"  language, 
we  shall  find  its  purest  form  in  a  frog  pond  on  a  summer 
night.  In  the  years  of  evolution  that  voice  developed  in 
various  directions  and  was  put  to  various  ends,  but  wherever 



there  is  voice  there  is  a  sensori-motor  mechanism  back  of  it. 
This  mechanism  reaches  great  perfection  among  birds  and 
mammals,  especially  among  Primates. 

Can  monkeys  talk?  They  do:  in  articulate  speech,  by 
grimaces,  by  signs.  They  talk  all  they  need  to;  they  under' 
stand  one  another.  To  that  extent  their  language  is  as  definite 
as  ours.  The  more  one  studies  the  apes,  the  greater  the 
puzzle  as  to  why  they  do  not  learn  to  speak  English;  we  do 
not  yet  know  that  they  cannot.  But  it  is  conceivable  that  a 
chimpanzee,  brought  up  from  birth  and  conditioned  by  human 
voices,  could  learn  to  distinguish  and  make  response  to  several 
hundred  words. 

Accustomed  as  we  are  to  regulated  flows  of  conversation, 
monkey  and  other  mammal  talk  seems  largely  exclamations: 
cries  of  rage,  fear,  pain,  courtship,  etc.  It  is  emotional 
language.  Monkeys  especially  have  a  large  repertoire  of 
finely  shaded  emotional  calls.  How  many  and  what  the 
shades  and  tones  signify,  we  do  not  know.  There  are  individ- 
ual variations;  the  mother  monkey  knows  when  her  own 
youngster  shrieks  for  help. 

That  is  about  the  extent  of  our  inherent  repertoire.  We 
can  all  cry  and  grunt,  and  we  have  our  own  key  and  pitch; 
with  that  our  voice  training  begins.  A  mother  easily  dis- 
tinguishes the  cry  of  her  child  from  among  twenty-five  babies 
in  a  nursery.  These  cries  presumably  diff'er  with  emotional 
states — hunger,  pain,  rage,  fear,  etc. 

Within  thirty  days  a  normal  infant's  voice  begins  to  roam 
around,  as  its  hand  and  arm  do;  as  though  it  were  trying  its 
voice  out.  It  has  a  vocal  mechanism;  it  exercises  it.  All 
living  mechanisms  are  excitable,  tongue  especially.  A  cur- 
rent of  air  is  always  available  in  breathing;  that  current 
flows  between  vocal  cords  and  through  a  resonator.  Lips  in 
certain  position,  tongue  in  certain  position,  cords  vibrating: 
sounds  result. 

It  is  a  long  road  between  early  random  sounds  and  the 
first  word,  as  it  is  between  random  reachings  out  and  grasp- 



ing  a  cup.  But  a  sound  is  a  sound  and  the  ear  of  the  child 
hears  the  sound.  The  sound  means  nothing  definite  to  the 
child's  ear  at  first.  Early  sounds  are  as  general  and  as  aim- 
less as  random  squirmings  elsewhere  in  its  body  mechanism. 
Some  excitatory  stimulus — a  pin,  a  tight  bandage,  oxygen  or 
food  starvation,  thirst,  slamming  of  a  door,  the  glow  of  a  full 
stomach,  the  comfort  of  a  warm  bed — is  impulse  for  action. 
Its  range  of  reactions  is  limited  and  as  yet  unlearned,  untu- 
tored by  experience.  It  has  not  learned  definite  responses. 
It  has  not  yet  learned  to  walk  to  the  tap  and  draw  a  cup  of 
water;  it  has  not  yet  learned  that  "Dink!"  will  bring  the 

The  baby's  ear  hears  the  sound;  it  makes  it  again,  as  it 
reaches  for  its  toe  again  once  it  has  discovered  how.  And 
again.  And  again.  In  all  living  matter  nothing  functions 
as  fast  as  babies.  M,  N,  NG,  H,  W,  Y,  R,  OW,  0,  E,  long  A, 
short  A:  all  in  thirty  days.  Hearing  others  produce  these 
sounds  becomes  stimulus  for  repeating  them.  Baby  is  given 
a  rattle  and  says,  "Oh."  Mother  says,  "Oh,  baby."  Baby 
bangs  the  rattle  and  chatters,  "Oh,  oh,  oh,"  like  a  magpie. 
It  has  begun  to  learn  English. 

But  habits  of  language  begin  somewhat  later  than  other 
activities  such  as  are  performed  with  hands,  arms,  legs.  Be- 
fore baby  can  say  "water"  or  "drink"  it  has  learned  appro- 
priate responses  to  hundreds  of  objects  and  many  complex 

With  more  vocal  building-blocks  more  sounds  are  pro- 
duced. There  comes  a  day  when  baby  wants  something.  It 
jabbers  away.  And  finally  says,  "Dada."  Great  excitement. 
Wants  its  father!  He  is  produced.  It  was  not  father  that  was 
wanted.  Other  articles  are  produced.  A  rag  doll.  That  is 
what  baby  wants!  "Dada"  means  rag  doll!  "Dada"  may 
be  the  baby's  word  for  rag  doll  for  months.  Every  baby 
has  its  own  vocabulary.  Words  become  substitutes  for  bodily 
movements.  Language  habits  replace  bodily  habits.  Before 
the  baby  can  understand  the  language  of  its  parents,  the 



parents  understand  the  baby's  language — and  jump  accord- 
ingly. For  babies,  as  Watson  says,  enjoy  such  tyranny  as  is 
rarely  displayed  by  the  crowned  heads  of  history. 

Endless  repetition.  Tryings  out,  tryings  on.  A  slow  proc- 
ess. But  fast  time  once  a  real  start  is  made.  "Dog"  at 
first  means  dog,  also  cat,  also  bone.  The  meanings  of  words 
become  restricted;  the  words  themselves,  whether  spoken  or 
heard,  more  definitely  conditioned.  "Dada"  gives  way  to 
"doll"  and  "daddy."  The  baby's  vocabulary  is  replaced  by 
parents'  vocabulary.  The  useless  and  random  sounds  and 
words  disappear;  those  which  bring  results  are  retained. 

The  learning  processes  involved  in  conditioning  the  appe- 
tite, using  knife  and  fork,  and  taking  food,  are  all  the  same. 

A  girl  of  twenty-eight  months  has  a  vocabulary  of  400 
words;  a  boy  of  forty-three  months,  960  words;  a  boy  of 
fifty-four  months,  2,000  words — enough  to  carry  a  moron 
through  life.  The  college  graduate  rarely  knows  more  than 
5,000  words. 

Language  is  part  of  human  adjustment,  learned  as  other 
actions  or  habits  are  learned.  Every  normal  newborn  has  the 
potential  ability  to  learn  to  talk  English,  Kwakiutl,  Chinese, 
Zulu — any  language.  He  learns  one — English,  let  us  say; 
learns  it  well.  At  twenty  it  will  be  difficult  for  him  to  learn 
French,  more  difficult  to  learn  Zulu;  by  the  time  he  is  fifty 
it  will  be  very  difficult,  so  difficult  that  few  do  it.  English 
is  of  little  help  in  learning  Kwakiutl:  one  goes  head  first,  the 
other  goes  feet  first. 

Each  language  employs  certain  phonetics  and  proceeds 
after  its  own  grammatical  form.  In  learning  English,  speech 
organs  and  ears  are  trained  to  English  phonetics,  to  the  rules 
of  English  grammar.  Over  a  hundred  muscles  are  involved ; 
delicate  adjustments  of  an  extraordinary  complex  mecha- 
nism ;  to  say  nothing  of  the  tongue  itself.  This  neuro-muscular 
mechanism  learns  English:  English  is  its  habit.  To  learn 
English  phonetics,  other  hundreds  of  possible  sounds  and 



word  combinations  have  been  neglected ;  they  can  be  rescued, 
if  at  all,  with  difficulty. 

A  pair  of  chopsticks  and  knife-fork-spoon  are  about  as 
diflferent-looking  objects  as  one  can  easily  imagine.  They 
seem  to  have  nothing  in  common.  So  with  English  and 
Chinese,  spoken  or  written.  The  two  languages  do  not  look 
alike;  they  sound  as  unlike  as  cat  and  canary  talk.  With  the 
same  inherent  equipment  of  muscles  and  organs  the  child 
learns  to  eat  with  chopsticks  and  talk  Chinese  if  brought  up 
in  a  Chinese  household;  or  to  eat  with  knife-fork-spoon  and 
talk  English  if  brought  up  where  such  eating  tools  are  the 
fashion  and  English  is  the  mother  tongue.  Children  of 
English  parents  brought  up  in  India  or  China  often  learn 
first  the  manners  of  eating  and  the  speech  of  their  native 
nurses.  A  resounding  belch  after  the  meal  is  "good  man- 
ners" in  certain  parts  of  the  world.   Manners  are  habits. 

If  the  baby  hears  baby-talk,  baby-talk  will  be  its  first 
language,  its  mother  tongue.  It  may  never  feel  so  much  at 
home  in  any  other  language.  Even  tones  are  learned.  Every 
child  can  learn  to  whine  or  talk  through  its  nose,  or  to  speak 
in  coarse  or  harsh  tones.  If  such  have  value  in  the  house- 
hold, the  baby  will  learn  to  fix  their  value.  A  dozen  words 
from  a  two-year-old  may  "speak  volumes"  for  the  house- 

In  hundreds  of  languages  there  is  a  distinct  word  meaning 
water;  and  several  ways  of  pronouncing  "water"  in  English. 
Why  so  many  words  for  the  same  thing,  so  many  ways  of 
pronouncing  the  same  word?  Each  language  has  its  own 
short-cuts  to  verbal  activity,  its  own  verbal  response  to  H2O. 
You  pronounce  w-a-t-e-r  one  way,  I  pronounce  it  another: 
we  learned  it  that  way.  Having  learned  it  that  way,  we 
react  to  other  pronunciations  of  "water"  as  we  react  to 
other  forms  of  behavior  differing  from  our  own.  If  we  wait 
until  we  are  grown,  we  find  it  difficult  to  pronounce  "Z'eaz^" 
as  the  Frenchman  does — or  understand  his  idea  of  water.  We 
get  set  in  our  ways.    Our  vocal  structure  gets  set  in  its  ways. 



Especially  the  larynx.  Between  twelve  and  fifteen  it  under- 
goes great  structural  change. 

Removal  of  the  larynx  removes  the  vocal  cords  and  so 
destroys  the  capacity  to  speak  aloud.  But  as  long  as  an  air 
passage  is  open  from  lungs  to  pharynx  and  mouth,  whispered 
speech  is  possible.  If  the  passage  is  closed  so  that  one  must 
breathe  through  an  opening  in  the  trachea  below  the  larynx^ 
there  can  be  no  whispered  speech.  Such  cases  are  known: 
they  can  speak  neither  in  nor  above  a  whisper;  yet  they  learn 
to  make  all  the  movements  necessary  for  articulate  speech. 

From  all  of  which  Watson  argues  that  thinking  is  action 
in  a  certain  motor  mechanism,  as  winking  is  action  in  a  cer- 
tain motor  mechanism.  We  think  in  words;  words  are  lan- 
guage mechanism  activity.  Hence,  thought  is  language 
mechanism  in  action.  Destruction  of  enough  of  that  mecha- 
nism to  make  impossible  any  of  the  movements  involved  in 
speech  is  to  make  thought,  and  probably  life,  impossible. 

Certain  phases  of  human  culture  certainly  would  be  impos- 
sible without  language.  Nor  is  any  culture  known  without 
its  linguistic  constituent.  As  Kroeber  says,  it  is  difficult  to 
imagine  any  generalized  thinking  without  words  or  symbols 
derived  from  words.  Religious  beliefs  and  certain  phases  of 
social  organization  such  as  caste  ranking,  marriage  regular 
tions,  kinship  recognition,  and  law,  also  seem  dependent  on 
speech.  But  it  is  conceivable  that  certain  inventions  might  be 
made  and  the  applied  arts  developed  in  a  fair  measure  by 
imitation  among  a  speechless  people.  How  and  why  primi- 
tive man  alone  of  the  Primates  developed  the  faculties  for 
speech  and  culture  remain  a  profound  puzzle. 


For  over  two  years  the  child  has  been  using  words,  but  only 
after  two  years'  trial  and  error  and  constant  effort  and  end- 
less corrections  can  the  child  be  said  to  have  a  well-organized 
verbal  behavior.    From  the  age  of  three  and  on,  word  and 



kinestlietic  organizations  are  put  on  simultaneously.  By  the 
time  we  are  four  we  have  added  to  our  kinesthetic  and  emo- 
tional organization  a  third  element  of  behavior:  we  can  talk; 
we  can  react  with  words. 

We  begin  our  word  organizations  early.  We  learn  "ball" 
and  a  ball.  We  learn  what  follows  when  we  do  not  respond  to 
"Don't!"  "Blow  your  nose!"  "Stop  teasing  little  sister!" 
"Bad  boy!"    "Shame  on  you!" 

Very  shortly  the  infant's  world  is  largely  words — together, 
serving  as  stimuli  to  call  out  reactions.  The  times  without 
end  that  we  react  to  "Let  that  alone!"  As  a  consequence  we 
come  to  answer  a  vast  word-world  with  words.  The  word-or- 
ganization dominates.  The  sensori-motor  throat-mechanism 
becomes  the  controlling  segment  of  the  body.  The  tongue 
becomes  gifted! 

We  can  remember  our  games  of  marbles  and  ball,  and  the 
birds'  nests  we  robbed,  and  the  early  swims  in  the  creek,  and 
the  arrowheads  we  found,  and  the  hundreds  of  actions  per- 
formed after  three  or  four  years  of  age,  because  we  talked 
about  them  at  the  time.  How  well  we  remember  them  depends 
on  the  extent  to  which  our  word  organization  paralleled  such 
bodily  actions  and  the  amount  of  emotional  reinforcement 
accompanying  such  actions. 

Thus,  word  organization  that  accompanied  explicit  body 
organization  plays  two  roles  in  behavior:  we  can  always  talk 
about  it,  memory;  we  can  by  words  begin,  correct,  modify, 
or  control  the  total  reaction. 

I  can  talk  about  learning  to  swim;  I  cannot  talk  about  learn- 
ing to  walk.  Learning  to  swim  was  accompanied  by  talk — of 
swimming.  Learning  to  walk  was  accompanied  by  bumps 
and  bruises — often  vocalized  but  not  verbalized.  In  later 
years  a  bump  on  the  shin  or  a  fall  on  the  ice  generally  finds 
us  speechless  but  rarely  emotionless. 

By  the  time  we  reach  school  we  solve  problems  on  paper: 
build  houses  and  bridges,  explore  the  Amazon,  cross  Asia 
with  Marco  Polo,  conquer  Europe  with  Napoleon,  write 



books,  edit  newspapers,  make  love  to  Dido.  There  is  no  end 
to  this  verbal  organization,  no  limit  to  our  capacity  to  make 
verbal  response.  Only  memory  sets  the  limit  to  the  problems 
that  can  be  solved  with  words. 

But  we  do  not  always  say  the  word.  The  stimulus  to  call 
a  man  a  cur  may  be  great:  we  repress  it  and  "get  hot  under 
the  collar";  or  to  pronounce  the  name  of  a  loved  one:  we 
repress  it  and  blush  or  giggle;  or,  think  it  over. 

Every  word  of  the  400  the  girl  of  twenty-eight  months 
knows  is  a  conditioned  reflex.  Her  eye  sees  candy;  her 
mouth  waters  candy;  her  voice  says  candy;  she  says  candy 
until  she  gets  it:  all  learned  responses,  all  habits,  all  reflexes. 
To  say  "candy"  is  an  explicit  act  of  behavior;  it  implies 
stimulus,  receptor-conductor-eff'ector.  The  eff'ector  was  the 
voice  mechanism,  the  speech  organ.  Suppose  she  had  not 
said  candy  but  thought  candy:  would  this  have  been  an  act 
of  behavior?    Is  thinking  candy  a  reaction? 

We  talk  to  ourselves,  some  incessantly.  We  call  it  "think- 
ing out  loud."  It  is:  thinking  aloud.  Many  never  learn  to 
read  without  moving  the  lips ;  closer  inspection  of  their  throat 
shows  all  the  muscular  movements  involved  in  reading  aloud, 
except  in  the  vocal  cords.  They  move  their  lips  because  they 
have  never  completed  the  transition  stage  between  explicit  and 
implicit  language  habits,  between  talking  and  thinking. 

Children  talk;  and  keep  on  talking.  They  are  responding 
to  stimuli.  There  comes  the  stimulus:  "Keep  still  or  I'll 
..."  They  keep  right  on  talking — but  to  themselves.  They 
learn  the  new  habit  of  talking  without  articulating;  the  vocal 
cords  do  not  participate  in  the  action.  By  and  by  they  learn 
to  drop  even  overt  lip  movements.  They  can  think  the  word 
hunger  without  overt  movement  of  any  of  their  laryngeal- 
throat-mouth  mechanism.  The  taking  on  of  such  habits  begins 
early  and  involves  no  new  or  strange  process  either  in  learn- 
ing or  in  the  conditioning  of  reflex  arcs.  Almost  as  soon  as 
the  child  can  talk  it  is  told  not  to  talk.  But  the  child  has 
already  learned  to  make  adjustments  with  words.    By  trial 



and  error  it  learns  to  drop  its  voice,  to  whisper,  and  finally 
to  dispense  with  all  overt  movement.  It  is  now  a  real  thinker, 
A  shrewd  observer  and  a  good  lip-reader  can  read  the  thoughts 
of  others  who  have  not  learned  to  think  except  in  overt  move- 

"Now  think  of  something;  think  hard!"  You  think  of, 
say,  beefsteak.  To  your  chagrin  and  amazement,  the  clever 
observer  says,  "You  are  thinking  of  beefsteak!"  Try  it  on 
yourself.  But  there  are  those  whose  thoughts  cannot  be  read. 
They  can  think  without  overt  muscle  contraction,  so  short- 
circuited  and  abbreviated  has  become  the  habit.  The  ob- 
server's eye  detects  no  sign  of  movement,  but  could  we  apply 
delicate  instruments  capable  of  picking  up  nerve  impulses 
and  detecting  faint  muscle  contractions,  we  should  find  that 
thinking  "beefsteak"  differs  from  saying  "beefsteak"  only  in 
degree  of  action. 

I  enter  a  restaurant  with  my  stomach  crying  food  and 
my  mouth  watering  beefsteak  and  my  throat  thinking  beef- 
steak. I  sit  down  in  a  chair.  That  stimulates  the  waiter:  he 
responds  with  ice-water,  etc.  But  I  want  beefsteak.  I  can 
make  that  want  known  by  several  methods:  I  can  make  a 
picture  of  it;  describe  it;  point  to  it  on  the  menu  or  to  a  plate 
of  it  on  another  table;  or  produce  one  from  my  pocket  and 
make  signs  of  more.  Any  one  of  these  methods  might  stimu- 
late the  waiter  to  action.  But  he  is  in  the  habit  of  respond- 
ing to  word  stimuli.  I  say,  "Beefsteak."  That  word  spoken 
within  his  hearing  brings  quick  results.  And  with  a  beefsteak 
I  am  adjusted — to  food. 

The  chief  business  of  thinking,  as  implicit  language  proc- 
esses, is  for  individual  adjustment.  The  supreme  value  of 
language  is  as  an  instrument  of  adjustment  in  social  organi- 
zation. Because  of  language  the  situations  which  confront 
individual  members  of  society  are  extraordinarily  complex 
and  infinitely  varied.  Most  of  these  situations,  or  stimuli,  are 
word  situations;  we  can  adjust  with  words.  Sometimes  we 
"Katy  did!"  "Katy  didn't!"  the  whole  night  long. 



Of  course,  we  think  with  our  entire  body.  Our  entire  bodily- 
organization  is  at  work:  at  times  at  a  high  rate,  at  times 
low;  at  almost  all  times  one  part  is  more  active  than  another. 
Rarely  do  we  get  into  action  with  our  bodily  organization 
functioning  as  a  unit  and  to  the  limit  of  its  capacity.  The 
body  thinks,  now  here,  now  there,  and  the  responses  are 
always  in  keeping  with  the  conditioned  reflexes  in  implicit  as 
well  as  in  explicit  mechanism.  We  do  not  reveal  all  our 
thoughts,  nor  always  even  think  them  in  words  to  ourselves; 
nor  does  an  ameba  or  a  cat.  Our  bill  of  inherited  "rights" 
is  not  less. 


Man  is  a  talking  animal  and  because  he  can  talk  has  in- 
creased his  response  mechanism  beyond  measure.  Most  of 
our  adjustments  are  with  words,  and  for  most  of  us  the 
older  we  get  the  more  we  rely  on  words.  Our  verbalized 
organization  dominates  our  life.  But  our  earliest  and  our 
last  responses,  and  many  in  between,  are  speechless,  part 
of  our  unverbalized  behavior;  we  only  look  the  part,  by  a 
smile  or  a  frown.  Response  without  words  is  the  more  ancient 
mode  of  adjustment. 

Language  short-cuts  work  and  play  and  makes  culture  pos- 
sible, but  because  of  language  we  become  complexly  inte- 
grated. Words  become  loaded.  One  word  can  set  more  men 
marching  to  death  than  any  one  earthquake  ever  killed  or 
volcano  drove  from  home.  "Lend  me  five  dollars"  can  lead 
to  action  as  overt  as  a  wink  or  a  kick  on  the  shin.  If  "Lend 
me  five  dollars"  leads  to  explanations,  the  explanation  re- 
action is  also  overt. 

To  the  thousand  petty  annoyances,  discomforts,  and  sense- 
less situations  of  life,  few  of  us  have  any  reaction  beyond 
words:  "What  a  nuisance!"  "Isn't  it  a  shame!"  "That  ought 
to  be  remedied,"  "Some  day  they  will  do  better,"  etc.,  etc. 
We  pick  our  way  about  through  the  flotsam  and  jetsam  of 
stupidity  and  ignorance  of  yesterdays,  without  a  move  to 



clean  up  the  mess  beyond  words,  words,  words.  We  grow 
indignant  and  with  clenched  fists  and  flushed  face  exclaim  that 
we  could  show  them  what  we  etc.,  if  etc.  We  have  thereby 
fought  a  righteous  battle  for  the  good  of  the  cause.  Words, 
words,  words.    Even  the  air  is  full  of  words  these  days. 

We  bandy  words  as  boxers  spar  for  position.  We  play  our 
best  golf  in  the  club-house;  turn  the  rascals  out  in  hot  argu- 
ment in  the  smoking  car;  bring  peace  on  earth  good-will  to 
men  at  church ;  and  correct  our  bad  habits  and  save  up  money 
in  bed. 

If  you  will  listen  to  me  I  can  prove  to  you  that  I  am  an 
expert  golfer  and  that  I  am  really  interested  in  good  govern- 
ment: I  can  prove  it  with  words.  And  if  you  are  a  good 
fellow  you  will  take  me  at  my  word;  but  if  not,  you  will  brag 
about  your  golf  and  tell  me  what  you  would  do  if  you  were 

There  are  many  star  performers  with  their  verbal  organiza- 
tion who  rarely  let  their  bodily  motor  mechanism  get  into 
action:  he-men  who  never  fought  a  fight  or  played  a  game  of 
one-ole-cat,  golf,  or  tennis  in  their  lives;  reformers  who  were 
never  in  a  voting  booth. 

Even  talking  wears  some  people  out.  They  just  think. 
They  are  content  to  think  themselves  good  golfers,  good  citi- 
zens, good  Christians.  They  think  beautiful  thoughts,  poems, 
pictures,  music,  peace  on  earth,  etc.,  etc.  Even  thinking  tires 
some  people.  "In  winter  I  set  and  think;  in  summer  I  just 

"Don't  bother  father;  he's  thinking."  One  might  suspect 
him  of  being  asleep.  W^at  is  father  thinking  with?  His 
mind?  Is  thinking  action?  If  it  is,  and  if  he  is  thinking  hard, 
he  will  be  consuming  energy.  There  is  no  action  without 
energy.  If  father  can  think  without  energy  consumption,  he 
should  be  removed  to  a  museum  where  they  keep  mermaids. 

After  an  hour  "father"  rises,  puts  out  the  light,  and  goes 
to  bed.  That  may  have  been  his  regular  hour  for  bed.  Yet 
in  that  hour  he  may  have  done  the  "biggest  day's  work  of  his 



life."  He  may  have  reached  a  decision  "momentous"  in  his 
own  and  his  family's  life.  Great  Scott!  his  decision  might 
affect  the  destiny  of  nations! 

What  was  the  decision?  How  can  I  know:  he  said  nothing, 
made  no  move  or  sign,  no  overt  explicit  act  of  any  kind.  For 
all  I  know  he  may  have  decided  to  sell  the  car,  give  up  smok- 
ing, change  his  bootlegger,  run  for  President,  or  declare  war. 

"Well,  fellows,  what  do  you  think  about  it?"  One  nods; 
one  shakes  his  head;  one  turns  his  thumbs  down;  one  shrugs 
his  shoulders;  one  winks;  one  whistles;  one  clears  his  throat. 
The  last  "fellow"  rises  to  emphasize  his  remarks:  "Well, 
fellows,  if  you  ask  me  what  I  think,  I  say:  Oh,  hell!  That's 
what  /  think!" 

The  "fellows"  usually  voice  what  they  think.  One  word 
stimulates  another:  many  cannot  stop,  once  the  first  word  is 
uttered.  We  fight  countless  battles  with  words.  With  words 
we  fly  to  the  moon  and  build  castles-in-Spain.  In  fact,  the 
range  of  our  activities  is  only  limited  by  our  vocabulary. 
That  is  why  we  think  so  much:  one  word  stimulates  another; 
we  cannot  stop.  There  is  no  problem  we  cannot  wrestle  with 
in  thought.  Thinking  is  so  easy,  Watson  calls  it  laryngeal 

When  our  thinking  is  in  words  we  are  thinking  "out  loud" 
or  "to  ourselves."  The  latter  is  silent  laryngeal  itch.  The 
stimulus  for  such  thinking  or  silent  verbalization  need  not 
differ  from  any  other  stimulus  to  which  other  mechanisms  or 
higher  or  lower  centers  of  the  body  respond.  It  is  called  itch 
because  we  can  make  such  varied  responses  to  such  varied 
stimuli  without  "turning  a  hand" ;  it  is  so  much  easier  to  turn 
it  over  to  the  mind.  "I  will  think  about  it." 

The  stimulus  that  sets  us  thinking  may  come  from  within : 
hunger,  sex,  etc.  More  generally  from  without:  anything  in 
the  environment,  from  a  house  falling  on  us,  to,  "Come!" 

And  so  we  "think  it  over"  in  unvoiced  words.  If  our 
vocabulary  is  large  we  can  think  widely.  But  the  poorest 
of  us  can  in  our  thoughts  take  journeys  on  yachts,  endow 



charities,  win  ball  games,  paint  the  house,  kill  off  our  ene- 
mies, write  novels,  compose  operas.  Our  only  limit  is  words. 
As  there  is  a  verbal  substitute  for  every  object  in  the  world 
the  limit  of  the  world  we  can  carry  about  with  us  is  set  by  our 
verbal  organization. 

Father  may  have  thought  out  a  way  to  buy  a  new  car,  the 
stimulus  for  such  thinking  having  been  any  one  of  the  count- 
less stimuli  which  excite  people  to  think  new  car.  The  family 
will  ride  in  the  car  when  father  says  a  word,  nods  his  head, 
or  writes  a  check.  It  is  the  thinking  that  gets  into  the  picture 
that  counts. 

The  stimulus  of  an  empty  stomach  serves  the  newborn  for 
its  first  thought:  it  says  it  with  certain  general  bodily  move- 
ments; two  years  later  it  says  it  with  a  specific  mechanism 
which  makes  a  sound  like  "hungry."  Sixty  years  later  the 
response  may  be  the  same,  even  though  no  ear  can  hear 
the  word  of  the  man  who  thinks  it.  In  other  words  thinking 
may  be  kinesthetic,  verbal,  or  emotional.  If  we  are  hampered 
in  our  bodily  actions  we  talk;  if  our  verbal  thinking  is 
blocked  emotional  thinking  dominates  us.  The  final  act  may 
be  an  unverbalized  "judgment" — which  need  not  be  a  rational 
conclusion  but  is  likely  to  express  our  irrational  dislikes. 

In  silent  words  we  make  countless  adjustments.  To  think 
it  out  is  an  implicit  habit  of  response.  There  are  also  implicit 
hereditary  or  instinctive  responses,  as  in  changes  in  respira- 
tion, circulation,  and  the  whole  system  of  hormone  secretions. 
Explicit  habits  of  response  are  eating  with  a  knife  and  fork, 
playing  tennis,  staying  on  good  terms  with  one's  own  and 
the  opposite  sex,  etc.  There  are  also  explicit  hereditary  or 
instinctive  responses,  as  in  grasping,  sneezing,  etc.,  and  in 
the  emotional  reactions  in  rage,  fear,  and  love.  If  the  solu- 
tion of  a  thought-out  problem  is  not  translated  into  overt 
explicit  action,  spoken  or  written,  or  other  explicit  bodily 
reaction,  there  has  been  no  adjustment:  the  world  of  environ- 
ment is  just  what  it  was. 

Man's  responses  are  uniquely  his  own  because  he  has  so 



many  words  to  respond  with,  so  many  ways  of  modifying  his 
explicit  instinctive  responses,  so  many  degrees  of  emotional 


We  recall  Mother  Goose  without  effort,  even  long  poems 
of  childhood.  I  have  forgotten  my  Latin,  but  certain  Odes 
of  Horace  and  that  good  old  resounding  Dies  irce,  dies  ilia, 
I  do  not  forget.  Not  for  twenty  years  had  I  thought  of  a 
certain  jingle.  I  find  myself  in  the  midst  of  some  girls.  With- 
out warning,  and  to  my  surprise,  I  begin:  "Briar,  briar,  lim- 
ber lock  ..."  Where  has  this  counting-out  rhyme  been 
these  twenty  years? 

There  is  no  short-cut  to  learning,  nor  system  by  which  the 
memory  can  be  improved.  Goose,  Odes,  Hymn,  and  Briar 
were  learned,  over  and  over:  overlearned.  We  overlearn 
many  things  in  childhood  we  "never"  forget.  We  learn  much 
in  childhood  we  do  forget. 

Forgetting  is  in  proportion  to  learning;  the  more  we  learn 
it,  the  longer  we  remember  it.  Learning  is  a  soaking-in  proc- 
ess. Some  things  must  be  learned  many  times  before  they 
soak  in.  The  idea  that  we  forget  the  unpleasant  or  the  pain- 
ful because  it  is  unpleasant  or  painful  is  nonsense. 

We  learn  to  swim  in  youth.  If  we  began  each  spring  where 
we  left  off  each  autumn,  we  overlearned  it.  We  can  jump 
in  forty  years  later  and  swim.  So  with  driving  nails,  play- 
ing marbles,  etc. 

We  know  how  to  swim.  But  vivid  swimming  memories  are 
mostly  accessories:  the  thrashings  we  received  when  we  ar- 
rived home,  the  knotted  wet  shirts,  the  frenzied  efforts  to  dry 
our  hair.    They  were  emotionally  tied  in. 

Every  reaction  we  make  has  its  instinctive  and  emotional 
background,  its  explicit  and  implicit  factors.  Rhymes,  Bible 
lessons,  poems,  particular  conversations,  etc.,  remembered 
from  childhood  were  emotionally  tied  in  as  well  as  over- 
learned.   The  emotional  factor  is  of  great  importance  in  con- 



ditioning  reflex  arcs.  In  learning  to  swim,  drive  a  nail,  recite 
a  poem,  these  factors  get  tied  together  and  work  together. 

They  become  so  tied  together  that  one  of  certain  stimuli 
can  set  them  off.  What  was  in  the  situation  to  set  off,  "Briar, 
briar.  ..."  I  do  not  know.  It  may  have  been  one  of  a 
dozen  stimuli :  the  general  situation  itself,  something  peculiar 
in  the  situation,  etc.  This  is  certain :  my  overt  act  in  repeating 
the  jingle  was  in  response  to  an  adequate  stimulus.  We  call 
ourselves  self-starters,  but  we  start  in  response  to  a  stimulus 
whether  to  run,  climb  a  tree,  recite  a  poem,  or  think.  There 
was  some  stimulus  in  that  situation  which  recalled  past  ex- 
perience to  me. 

I  had  been  there  before,  as  it  were.  We  often  say  that, 
knowing  well  that  we  never  have;  and  call  it  mysterious. 
There  is  no  mystery  about  it.  Some  detail  in  a  situation, 
in  a  room,  in  a  man's  face,  vividly  recalls  some  past  ex- 
perience. The  recalled  detail  is  so  vivid  that  we  feel  we  have 
"been  there  before,"  have  "seen  that  man  before." 

Memory  does  play  strange  tricks.  But  it  seems  less  tricky 
if  we  think  of  it  in  terms  of  situation  and  stimulus.  WTien 
we  cannot  remember  our  own  name — and  sometimes  we  can- 
not— the  situation  is  one  in  which  we  have  had  no  experience 
in  remembering  our  name,  or  in  which  no  adequate  stimulus 
is  at  hand  to  break  through  other  stimuli  clamoring  for  atten- 
tion. Trying  hard  to  recall  it  makes  it  hard  for  the  adequate 
stimulus  to  appear.  The  next  morning  the  name  may  pop 
into  our  head.  The  stimulus  for  recalling  persisted;  there 
had  been  no  adjustment.  During  sleep  or  on  waking  the 
adequate  stimulus  gets  a  hearing:  the  name  "pops  into  our 

As  did  "Briar,  briar.  ..." 

Between  the  years  we  learned  to  swim  and  the  day  forty 
years  later  when  we  jump  in  again,  arms  and  legs  learn  no 
new  habits  which  make  swimming  mechanism  hard  to  func- 

The  childhood  lessons  that  are  forgotten  were  never  over- 



learned  or  were  built  into  other  learning.  We  remember  our 
A  B  G's  because  we  continue  to  use  them.  But  of  the  stories 
in  the  Readers  we  remember  only  our  favorites.  The  count- 
ing-out rhymes  were  repeated  so  often — as  was  Dies  irce — 
that  the  conditioned  reflex  chain  was  grooved.  "Ene"  was 
adequate  stimulus  for  "mene,"  and  so  on. 

It  requires  longer  to  learn  "Ura,  eyuk,  ro,  duni"  than  to 
learn  "Ene,  mene,  mine,  mo."  "Ene  mene"  does  not  make 
sense,  but  it  jingles.  It  requires  ten  times  more  practice  to 
learn  nonsense  than  sense  material.  And  the  longer  the  non- 
sense series,  the  longer  proportionate  time  required;  each 
syllable  must  become  tied  up  with  the  one  preceding.  Hence, 
nonsense  syllables  are  quickly  forgotten.  To  relearn  them 
eight  hours  later  requires  two-thirds  of  the  original  learning 
time.  There  is  no  such  forgetting  during  the  intervals  in 
learning  to  play  the  piano  or  the  typewriter. 

Boys  quickly  learn  to  swim;  it  becomes  a  habit  more 
easily  than  skating.  No  school  in  summer.  One  habit  is 
learned  more  quickly  than  two.  Learning  lessons  in  school 
formerly  progressed  slowly:  practice  periods  too  close  to- 
gether, too  little  incentive. 

We  can  learn  only  so  much  of  any  one  thing  in  one  day. 
But  between  times  we  can  learn  something  else.  If  it  is  a 
poem,  game,  or  complicated  process,  we  learn  it  more  easily 
and  remember  it  longer  if  we  learn  it  as  a  whole.  The  way 
to  learn  Paradise  Lost  or  a  part  in  a  play  is  not  line  by  line, 
but  as  a  whole.  When  learned  as  a  whole  it  is  remembered 
as  a  whole;  when  learned  line  by  line  it  is  so  remembered: 
it  is  not  so  well  tied  in.  We  know  a  thing  "by  heart"  when 
our  memory  anticipates  every  reaction  in  the  chain. 

It  is  the  stimulus  that  counts.  Rats,  mice,  guinea-pigs, 
birds,  and  cockroaches  learn  to  thread  an  elaborate  maze; 
even  at  the  cost  of  pain  if  the  stimulus  be  adequate.  Hunger, 
for  food  or  for  the  opposite  sex,  is  the  stimulus  used.  Old 
rats  require  longer  effort  and  more  trials  to  learn  to  thread 



the  maze.  But  no  rat  has  yet  been  found  too  old  to  learn 
to  thread  it! 

Within  reasonable  limits,  youth  learns  more  rapidly  than 
adult  age;  both  learn  in  proportion  to  incentive  to  habit 
formation  and  uniformity  of  height  of  incentive.  A  man  is 
as  old  as  he  is  incapable  of  learning. 

We  learn  only  if  we  have  the  incentive.  But  even  the 
reflex  time  of  knee-jerk  slows  up  if  repeated  at  once.  A 
joke  told  is  already  stale,  good  thereafter  only  to  the  teller 
when  he  can  find  new  victims.  One  lesson  was  enough  for 

Memory  is  looking  backward;  of  biologic  service  when  it 
impels  us  forward. 


"Don't  jump;  diveP^  Easier  said  than  done.  We  are 
organized  on  head-up,  feet-down  plan.  We  learn  to  walk 
that  way.  The  first  dive  is  a  new  experience:  it  reverses 
our  feet-down  head-up  and  away-from-solids  habit;  the 
water  looks  hard;  there  may  be  rocks  below.  There  were. 
The  boy  never  forgot  it — nor  learned  to  dive.  No  will  power 
inside  his  skull  could  cause  the  nerves  outside  to  forget  their 
lesson.    He  could  not  put  his  whole  heart  into  a  dive. 

Some  boys  can;  they  have  the  do-or-die  habit.  They 
explore  bottoms  and  dive  in  again.  And  again.  By  the  end 
of  the  week  they  dive  like  frogs.  Their  sisters  are  just  as 
good.  Do-or-die  for  one  is  usually  do-or-die  for  all  in  tlie 

The  boy  who  learned  to  dive  in  spite  of  his  first  mishap 
succeeded  largely  because  of  it.  The  problem  was  different, 
more  difficult  than  he  had  anticipated.  That  tapped  a  new 
source  of  zeal.  He  became  a  high  diver  in  the  circus.  A 
net  is  not  water,  but  the  skill  required  in  maneuvering  a 
head-first  body  in  diving  was  available  in  learning  to  dive 
from  the  top  of  the  big  tent. 

There  is  always  great  complexity  of  stimuli  in  any  given 



situation;  the  situation  itself  is  always  changing,  A  pig 
quietly  nosing  along  a  swill  trough  is  joined  by  two  more 
pigs.    New  situation  now:  the  first  pig  gets  into  the  trough. 

The  family  have  just  sat  down  at  the  dinner  table.  The 
door  bell  rings.  Behavior  of  the  entire  family  changes: 
mother  jerks  off  her  apron,  father  puts  on  his  coat,  sister 
wipes  brother's  mouth,  brother  kicks  the  cat.  New  situation; 
only  one  new  stimulus,  door  bell.  The  family  jumped  to 
the  reaction:  well  trained. 

Baby  alone  went  right  on  banging  his  spoon  on  the  arm 
of  his  chair.  Baby  had  just  acquired  that  habit  and  found 
it  so  stimulating  that  entrance  of  stranger  did  not  alter  its 
situation.  But  the  family  now  are  suddenly  conscious  of 
baby's  behavior.  Mother  asks  sister  to  take  baby  into  the 
kitchen,  knowing  that  removal  of  spoon  will  set  off  the  first 
habit  baby  learned  (crying  till  he  gets  it).  Baby  is  not 
likely  to  lose  that  habit:  no  other  one  yields  him  such  large 

We  become  Dr.  Jekyll  or  Mr.  Hyde.  Few  can  become 
both.  We  have  our  own  level  of  organization,  our  habits  of 
response  to  situations  in  which  we  feel  at  home.  But  Jekyll- 
Hyde  was  at  home  in  two  situations.  His  was  a  dual  per- 
sonality. In  one  set  of  situations  he  was  Dr.  Jekyll,  in  the 
other  Mr.  Hyde. 

There  are  times  when,  to  our  astonishment,  dog  or  child 
makes  no  response  to  name  or  other  stimulus  which  ordinarily 
calls  out  a  response.  If  we  cannot  predict  a  child's  response, 
how  can  we  expect  to  predict  the  behavior  of  an  adult?  How 
can  we  know  when  Mr.  Hyde  will  turn  into  Dr.  Jekyll? 

We  cannot.  Even  prediction  of  a  comet's  movements  is 
simple  compared  with  predicting  the  behavior  of  an  ameba. 
But  there  are  some  general  principles  that  are  of  general 

Our  response  to  a  kick  on  the  shin  may  be:  "Well,  I'll 
be  .  .  ."  That  response  does  not  follow  if  we  are  in  church, 
even  though  the  kick  came  from  the  same  brother.  The 



situation  as  a  whole  is  a  determining  factor.  The  response 
is  delayed  until  the  situation  is  right.  In  Rome  we  do  as 
the  Romans  do.    Ditto  in  church,  at  a  ball  game,  at  a  ball. 

The  response  is  likely  to  be  a  repetition  of  one  recently 
called  out.  We  have  not  been  to  a  movie  for  months:  a 
friend  drags  us  out;  we  go  to  a  movie  every  night  for  a  week. 
I  have  just  visited  a  maple-sugar  camp:  I  now  notice  maple 
trees  everywhere ;  and  see  sugar  cakes  in  the  grocer's  window. 
I  passed  them  by  this  morning  without  noticing  them. 

A  fire  engine  shrieks  through  the  street  several  times  a 
week.  I  have  long  since  ceased  to  notice  it.  I  do  to-day: 
my  fire  insurance  expired  yesterday.  I  am  all  excited 
because  I  intend  to  listen-in  to-night:  the  President's  speech 
is  to  be  broadcast.  I  make  certain  that  my  radio  is  in  order. 
At  eight  o'clock  I  have  the  colic:  the  President's  speech  means 
nothing  to  me. 

My  response  to  a  knock  on  the  door  may  be  to  open  the 
door;  I  may  lock  it,  turn  out  the  light,  and  reach  for  a 
revolver.  I  may  pray.  Vast  numbers  of  our  responses  are 
made  with  words.  This  doubles  our  response  repertoire, 
complicates  our  behavior. 

Four  brothers — a  banker,  a  preacher,  a  paleontologist,  and 
a  bootlegger — read  the  news  of  the  sinking  of  the  XVIIIth 
Amendment:  predict  the  response  of  each.  The  door  bell 
rings,  a  man  enters;  it  is  their  enormously  rich  Uncle  Bim 
from  Australia.  The  situation  is  again  changed.  But  to 
each  and  to  all  situations  an  almost  unlimited  number  of 
varying  responses  was  open  to  each  of  these  four  men.  And 
is  open  to  all  of  us. 

There  are  also  two  ways  of  clothing  our  nakedness — for 
we  are  born  naked  and  are  not  ashamed  of  it.  But  the  over- 
dressed man  and  the  underdressed  woman  had  the  same  start 
and  are  only  happy  when  they  are  noticed:  on  the  stage  or 
platform,  or  in  the  pictures  or  a  lodge  parade.  When  a 
woman  cannot  make  an  exhibition  of  herself  any  other  way 
she  can  start  a  dress-reform  movement. 



Human  beings,  acting  and  reacting.  The  situations  which 
call  out  reactions  are  diverse.  The  response  any  given  indi- 
vidual will  make  to  any  given  situation  is  a  variant  and 
depends  upon  that  individual's  previous  experience,  includ- 
ing such  things  as  cold  toast  that  morning,  the  reading  of 
The  Marble  Faun  ten  years  before,  a  fight  twenty  years 
before  that.    Individual  behavior. 

Yet,  as  Watson  says,  it  is  almost  impossible  for  a  balanced 
man  to  be  so  torn  as  to  steal  his  neighbor's  purse  or  child, 
or  to  commit  suicide  or  mutilate  others.  Such  responses  are 
possible  only  to  the  extent  that  the  co-ordinations  used  in 
committing  such  crimes  are  in  his  behavior  repertoire. 
Furthermore,  his  total  reaction  systems  are  so  tied  together 
that  the  moment  he  starts  to  commit  suicide  or  a  crime  a  new 
situation  is  created  and  leads  to  a  different  act.  It  is  quite 
impossible  for  most  of  us  to  commit  suicide;  our  conditioned 
fears  and  our  unconditioned  responses  will  not  let  us.  Prac- 
tically all  our  suicides  are  pathological — diseased  personal- 
ity.  Suicide  in  Japan  or  China  may  be  normal  behavior. 

We  are  not  mosaics  of  inherent  reflexes  and  learned  habits, 
but  we  are  going  concerns.  How  we  go,  how  fast  we  go,  and 
what  we  go  in  or  out  for,  depend  on  the  situation  and  our 
experiences  with  previous  situations.  "We  act  in  line  with 
our  training  and  in  conformity  with  our  inherited  points  of 
weakness  and  strength."  The  situation  we  are  in  dominates 
us  and  releases  one  or  the  other  of  our  all-powerful  habit  sys- 
tems— we  exhibit  our  learning  in  the  manual,  laryngeal,  or 
visceral  field.  A  cross-section  of  our  habit  systems  in  these 
three  fields  gives  us  a  picture  of  our  personality. 


We  learn  new  responses  for  adjustment  purposes  and  in 
taking  on  habits  are  subject  to  factors  which  condition  all 
learning.   We  become  adapted,  positively  or  negatively:  the 



stimulus  reaches  us  more  easily  or  we  inhibit  it  with  less 

A  doctor  asleep  beside  his  wife  hears  only  the  telephone; 
she  hears  only  the  baby.  But  if  the  baby  cries  long  enough 
he  will  hear  it,  and  if  the  telephone  rings  long  enough  she 
will  hear  it.  There  is  a  limit  to  adaptation.  Both  can  hear 
a  mouse  or  a  burglar.  Most  boys  can  hear  a  penny  drop; 
most  men's  ears  pick  up  nothing  less  than  silver. 

Tight  shoes  are  only  tight  until  we  get  used  to  them.  It 
is  the  sudden  drops  in  the  temperature  that  we  notice.  We 
grow  accustomed  to  change  if  it  is  gradual:  bad  air,  bad 
food,  bad  government,  bad  wives,  bad  husbands,  bad  chil- 
dren, high  cost  of  living.  Life  can  make  huge  concessions 
if  it  is  not  crowded  or  pushed.  As  long  as  the  breaking 
point  is  not  reached,  we  can  stand  it.  Wives  at  fifty  will 
look  just  as  good  as  at  twenty — if  the  change  has  been 
gradual.    We  can  become  adapted  even  to  lethal  doses. 

When  any  given  stimulus  sufficient  to  set  off  the  response 
mechanism  is  repeated,  the  threshold  is  lowered  and  the 
response  hastened:  we  are  positively  adapted,  favorably  dis- 
posed. We  are  negatively  adapted  if  the  stimulus  is  grad- 
ually increased  without  increased  or  with  delayed  response, 
or  if  the  threshold  is  permanently  raised.  If  we  fail  to  get 
up  with  the  alarm  clock  we  soon  fail  to  hear  it. 

We  have  a  "hangover"  after  intense  and  emotionally 
stimulated  activity.  After  a  long  session  at  cards,  our  minds 
go  right  on  playing  cards.  We  "pop  the  question"  on  a 
moonlight  night  after  a  preliminary  warming  up.  Warming 
up  lowers  the  threshold  and  has  psychologic  value  in  all 
fields  of  activity  where  we  are  out  for  victory. 

Why  do  we  like  certain  poems,  pictures,  songs,  melodies, 
hymns?  I  sat  through  a  Georgia  camp  meeting  recently. 
The  preacher  exhorted  and  exhorted;  no  one  came  "forward." 
Then  another  old  familiar  air  was  set  in  motion:  many  went 

Leaders — in  religion,  politics,  and  business — get  "results" 



because  they  know  how  to  play  on  us.  We  buy  or  bite  not 
according  to  our  requirements  or  on  the  strength  of  the 
merits  of  the  "goods"  they  sell  us  (for  they  rarely  talk 
merits),  but  according  to  their  appeal  to  our  attitudes. 

We  go  to  a  political  rally.  Flags  everywhere;  pictures 
of  Washington  and  Lincoln  on  the  stage.  That  stage  is  set 
for  us;  the  trap  is  baited.  We  do  not  need  these  settings; 
but  they  do  their  work:  they  make  us  favorably  disposed. 
We  cannot  look  at  Our  Flag  or  the  Father  of  Our  Country 
without  being  moved.  Prayer  follows:  God,  save  America 
and  bless  the  man  who  is  about  to  save  it.  Etc.  Then  the 
speaker  talks  about  Lincoln  and  drags  in  other  matter 
irrelevant  to  his  own  fitness.  And  we  are  further  moved. 
And  with  an,  "All  together!"  we  sing  "America."  That 
decides  us:  he  is  the  man  we  want. 

The  successful  politician  may  never  have  heard  of  "emo- 
tional tendencies  built  up  through  association  processes"  or 
of  "conditioned  emotional  responses,"  but  he  does  not  try 
to  sell  himself  to  a  Georgia  rally  with  a  eulogy  on  Sherman 
or  ask  all  to  rise  and  sing  "John  Brown's  Body."  Nor  does 
the  salesman  try  to  sell  refrigerators  to  Eskimos  or  the  com- 
plete works  of  Darwin  to  South  Carolina. 

Whether  we  are  positive  or  negative  all  depends.  But  we 
are  positively  adapted  for  anything  and  everything  that 
interests  us.  Whether  a  particular  thing  is  to  our  interest  or 
not  also  depends.   We  can  learn. 


The  principle  back  of  breaking  habits  is  the  same  as  that 
back  of  forming  them:  substitution.  Substitute  another. 
Sometimes  it  is  difficult;  the  path  may  be  worn  too  deep. 
Then  it  is  a  habit:  if  useless,  a  bad  one;  if  dangerous,  lock 
him  up. 

A  farmer  breaks  a  colt  gradually.  He  accustoms  it  to  the 
sight  of  things,  to  the  feel  of  things ;  little  by  little.   The  first 



thing  the  colt  knows,  it  is  hitched  up.  It  is  broken  to  har- 
ness. But  a  colt  can  have  its  conditioned  fear  reflexes.  And 
when  the  stimulus  comes — umbrella,  locomotive  engine, 
auto,  red  dress,  any  fool  thing — it  scares.  One  way  to  keep 
it  from  scaring  is  to  keep  it  away  from  fearsome  things.  A 
better  way  is  to  condition  it  to  men.  With  fear  of  men  gone, 
the  colt  begins  to  have  confidence  when  there  is  a  man  about. 

The  human  infant  has  almost  no  specific  fears.  Its  par- 
ticular fears  become  conditioned  and  terribly  real.  They 
can  be  conditioned  out,  gradually.  The  old  habit  of  being 
afraid  of  certain  things  or  persons  is  replaced  by  other 

As  the  weaning  day  approaches  many  babies  take  to 
thumbs.  The  thumb  satisfies  the  sucking  reflex,  an  instinctive 
act.  But  if  the  baby  is  not  allowed  to  get  its  thumb  in  its 
mouth,  the  sucking  reflex  will  disappear  along  with  other 
infantile  actions.  Elimination  functions  are  instinctive  and 
many  habit  activities  are  built  up  around  them.  Such  acts 
cannot  be  broken  up,  as  can  the  sucking  reflex,  but  they  can 
be  socialized  and  the  infant  can  be  taught  continence  with 
respect  to  them  very  early  in  life. 

Habits,  whether  inherent  or  acquired,  can  usually  be 
broken  up  by  altering  the  stimulus.  Horses  often  show  their 
fighting  instinct  by  kicking  or  biting  at  a  passer-by.  But  a 
horse  which  has  bitten  into  a  sleeve  of  cayenne  pepper  is  not 
likely  to  bite  into  another  sleeve.  If  the  figure  passing 
behind  him  is  a  dummy,  and  if  his  feet  are  jerked  from 
under  him  as  he  kicks  at  it,  he  will  think  of  his  feet  the  next 
time  he  is  impelled  to  kick.  The  dog  which  instinctively 
sucks  eggs  loses  his  appetite  for  eggs  after  he  has  crushed 
a  cayenne  pepper  prepared  egg.  The  instinctive  chain 
reflex  now  reads:  smell  egg,  hang  out  tongue  to  cool;  instead 
of :  smell  egg,  crack  it,  lap  it  up. 

Specific  fears  and  other  forms  of  emotion  generally  run  in 
families;  they  are  handed  down,  conditioned  in.  Children 
of  lion-tamers,  snake-charmers,  steeple-jacks,  etc.,  grow  up 



without  conditioned  fears  of  lions  or  snakes  or  high  places. 
The  son  of  a  snake-charmer  may  go  in  for  the  ministry,  but 
the  minister's  daughter  is  not  likely  to  become  a  snake- 

The  child  that  has  everything  it  wants  is  no  more  likely  to 
form  habits  of  thrift  than  a  Hottentot  or  a  monkey.  Habits 
are  not  formed  by  uttering  precepts.  Nor  is  moral  conduct 
founded  on  preachments.  Nor  a  bad  habit  broken  by  warn- 
ings. But  a  little  common  sense  and  a  few  lessons  in  the 
biology  of  reproduction  have  not  yet  been  known  to  encourage 
youth  to  bad  habits  and  have  been  known  to  make  for  sanity, 
peace  of  mind,  and  normal  behavior.  Much  of  the  drive 
behind  morbid  curiosity  in  the  young  springs  from  society's 
ban  on  such  matters.  The  ban  itself  only  makes  a  natural 
curiosity  morbid  and  adds  zest  to  the  gratification  of  that 

Our  erogenous  zones,  as  Ellis  calls  them,  function  from 
birth:  they  respond  to  stimuli.  The  baby  can  gurgle  and 
coo  and  smile  when  it  is  tickled  or  patted  or  pleased.  The 
hug  response  follows  the  outstretched  arm  movement.  Just 
where  love  comes  in  it  is  not  easy  to  say.  It  does  come — 
early;  it  does  get  conditioned  into  our  emotional  fears  and 
hates,  strengthening  them,  modifying  them,  coloring  them. 
Especially  into  our  attitudes,  even  toward  a  sunset.  Our 
emotions  get  more  or  less  saturated  with  sentiment.  Often 
the  mate-hunger  impulse  receives  more  than  its  share  of 
rebuffs.    These  lead  to  definite  attitudes  backed  by  emotion. 

The  lovesick  maiden  seeks  sympathy  and  the  lovelorn 
youth  solitude.  And  few  there  are  who  do  not  know  the 
meaning  of  shame,  envy,  hate,  jealousy,  shyness,  embarrass- 
ment, pride,  suspicion,  anxiety,  anguish,  resentment,  etc.; 
emotional  habits  conditioned  on  to  instinctive  tendencies. 
They  upset  us  in  dozens  of  ways ;  they  make  or  break  or  pre- 
vent marriage;  they  are  as  much  a  part  of  us  as  our  arms 
and  legs. 



Emotional  attachments  are  of  value  only  when  attached 
to  serviceable  or  useful  behavior,  when  called  out  under 
stress,  and  when  directed  to  the  big  business  of  life.  It  hurts 
to  be  scared  and  we  boil  when  we  are  enraged.  But  the  life 
that  always  boils  or  is  scared  cold  has  little  time  for  routine 
business  of  life. 

The  time  to  break  such  hurt  and  boil  habits  is  before  they 
are  formed:  before  the  emotions  have  become  specific  for 
things,  places,  and  people  that  are  not  changed  by  tears  or 
smiles.  Then  we  can  talk  of  moral  and  political  issues  with- 
out slopping  over  into  useless  sentimentality  or  boiling  over 
with  worse  than  useless  vindictive  animosity. 

This  is  not  easy.  It  is  easier  to  allow  our  emotions  to 
move  us  than  to  restrain  our  emotions  and  inquire :  where  do 
we  want  to  go  and  why  do  we  not  move  in  that  direction? 
Easier,  because  that  is  our  habit. 


Your  family  physician  can  put  you  to  sleep  with  a  drug, 
but  he  cannot  tell  you  why  you  suffer  insomnia  or  why  you 
can  walk  in  your  sleep.    Or  why  you  sleep — or  wake  up. 

One  popular  theory  solves  the  problem  with  thyroid  hor- 
mones. Muscle  activity  generates  poison — "fatigue  prod- 
ucts." Iodine  is  anti-toxic.  The  thyroid  furnishes  iodine. 
Hence  .  .  .  But  inasmuch  as  the  infant  sleeps  early  and  late 
and  cannot  be  presumed  to  have  generated  much  fatigue 
product  from  muscle  activity,  sleep  itself  was  assumed  to  be 
instinctive  biologic  defense  mechanism  to  prevent  intoxi- 

Which  explains  sleep  just  as  much  as  breathing  is 
explained  by  saying  that  we  breathe  in  order  not  to  become 
asphyxiated.  We  cannot  commit  suicide  by  holding  our 
breath,  nor  by  withholding  our  sleep.  Breathing  and  sleeping 
are  reflex  acts  which  travel  on  their  own.   The  muscle  toxins 



were  assumed.  It  was  then  presumed  that  the  th^Toid — or 
some  other  gland — washed  them  out. 

The  vasomotor  theory-  assumes  that  at  the  end  of  tlie  day 
the  center  of  the  nervous  system  which  regulates  the  size  of 
blood  vessels  gets  "tired.**  As  a  conse-ijuence  the  blood  sup- 
ply to  the  brain  is  panially  cut  off.  That  puts  die  b:.ii.:  to 
sleep.    Then  we  sleep. 

But  is  the  brain  robbed  of  blood  during  sleep,  does  action 
in  skeletal  muscles  lead  to  intoxication?  In  other  words,  is 
there  any  basis  in  fact  behind  the  commonly  accepted  theories 
of  the  cause  and  f miction  of  sleep?  \rhen  we  are  tired  we 
fall  asleep  more  easily  than  when  we  are  fresh.  But  the 
loafer  does  not  have  to  be  tired:  he  drops  off  to  sleep  at  his 
regular  hour — or  any  odier  hour.  \or  is  the  brain  robbed 
of  its  blood  during  sleep:  the  evidence  points  the  other  way. 
But  whether  the  brain  has  little  or  much  blood,  die  vasomotor 
change  may  be  the  conse<:pience  as  well  as  a  cause  of  sleep. 
Neither  explains  the  release  of  die  sleep  reflex. 

Kleitman  and  Lee.  working  on  a  human  subject  kept  a^vake 
for  115  hours,  could  find  no  evidence  of  g-       '    ^       - -  • 

either  in  the  carbon  dioxide  content  of  th-      . 

sugar,  heart  rate,  respiration,  temperature,  or  rate  of  basal 
metabolism.  The  theon.'  of  in: :  :  -^:'?n  at  the  end  of  ever\- 
sixteen  hours  falls  flat. 

Their  experiments  uncovered  other  facts  at  variance  widi 
popular  notions  about  sleep,  especially  as  to  die  efl'ects  of 
loss  of  sleep.  After  nearly  five  days  without  sleep,  the  sub-- 
ject  showed  no  variation  from  the  normal  in  a  larg-  r.ijer 
of  functions.  He  ate  and  worked  as  usual.  His  knee-kick 
and  eye-pupil  dilation  reflexes  vrere  unaff'ected.  So  was  his 
ability  to  do  mental  arithmetic,  to  name  opposite^,  and  to 
react  to  eye  and  ear  stimuli.  There  vras  no  change  in  his 
sensor}-  threshold  for  electric-current  stimuli.  He  did  lose 
some  control  of  the  muscles  of  his  head:  it  wobbled.  But 
that  may  have  been  due  not  to  insomnia,  but  to  tired  neck 



The  subject  could  keep  awake  only  by  continued  activity. 
An  attendant  accompanied  him  to  prevent  him  from  relaxing. 
Whatever  causes  sleep,  its  onset  begins  with  complete  relaxa- 
tion of  the  skeletal  muscles.  As  muscular  activity  invariably 
accompanies  and  is  perhaps  the  most  characteristic  feature 
of  wakefulness,  the  probable  cause  of  the  onset  of  sleep  is 
relaxation,  voluntary  or  involuntary. 

Sleep  itself  may  be  due  to  fatigue  of  the  highest  centers 
of  consciousness;  but  whether  to  loss  of  nutritive  substance 
in  the  nerve  cells  or  to  increase  of  waste  of  cell  metabolism 
is  not  known.  The  highest  centers  are  those  of  learned  con- 
trol and  association  of  motor  and  speech  mechanisms.  They 
are  the  most  recent  acquisitions  to  the  nervous  system,  the 
least  organized  at  birth,  the  most  modifiable  from  birth.  A 
small  dose  of  alcohol  affects  the  voice,  a  larger  dose  affects 
the  gait;  but  only  a  large  dose  paralyzes  the  respiratory  cen- 
ter: that  is  a  low  center. 

In  all  the  experiments  performed,  the  subjects  could  not 
study  after  one  night's  loss  of  sleep.  They  could  do  labora- 
tory work  and  mental  arithmetic,  etc.;  but  their  highest 
centers  gradually  lost  their  irritability,  as  ours  do  after  a 
long  day's  work.  Sleep  restores  this  irritability.  But  just 
what  else  happens  during  sleep  is  not  known. 

Dreams,  for  one  thing.  During  light  sleep  sensations  from 
the  viscera  or  from  outside  the  body  may  reach  lower  centers; 
they  are  older,  better  organized;  presumably  less  subject  to 
fatigue.  Dreams  are  not  critical.  These  sensations  do  not 
reach  the  highest  levels  of  the  cortex  where  only  they  can  be 
correctly  analyzed  and  interpreted.  If  they  become  so  strong 
as  to  force  their  way  into  the  highest  level  and  rouse  it  to 
action,  we  wake  up. 

Sleep,  then,  takes  the  kick  out  of  stimuli  that  in  waking 
hours  would  receive  attention  and  result  in  voice,  thought,  or 
motor  mechanism  reaction.  But  the  sleep-walkers!  Their 
dreams  get  into  their  high-level  motor  mechanism  and  they 



walk!    Why  walking  does  not  wake  them  is  not  yet  known. 

What  wakes  us?  Stimulus  from  stomach,  bladder,  or 
other  visceral  organ  finally  becomes  so  powerful  as  to  break 
through  synaptic  resistance  and  rouse  the  cortex.  We  are 

Why  do  we  sleep?    What  is  back  of  sleep? 

But,  first,  what  is  back  of  life  itself?  Sunlight.  The  sun 
is  the  primary  source  of  the  energy  of  green  plants;  in  sun- 
light they  build  up  their  bodies.  But  the  light  fails,  the  sun 
goes  down.  They  had  to  meet  that  condition,  to  find  the 
energy  required  to  prolong  life  throughout  the  night.  The 
problem  was  met  in  two  ways:  by  living  more  slowly — that 
is,  consuming  less  energy — during  the  night;  by  deriving 
energy  from  breaking  down  and  so  releasing  the  stored 
energy  of  their  own  body.  Process  of  katabolism,  or 
destructive  metabolism. 

Katabolism,  then,  is  an  adaptation  to  the  dark. 

Throughout  the  ages  since  life  evolved,  day  follows  the 
night.  Throughout  the  nights,  the  machine  of  life  slowed 
down;  it  could  not  build  up  its  body,  but  it  couldl  keep  it 
alive  until  the  day  came,  the  body  itself  furnishing  the 

We  eat;  the  sun  goes  down;  we  go  to  sleep.  The  sun 
comes  up;  we  wake;  we  eat.  During  sleep  the  processes  of 
metabolism,  especially  the  katabolic,  continue. 

Ages  ago,  our  ancestors  did  not  develop  electric  organs  or 
lucif  erase ;  they  did  develop  diurnal  habits.  The  nights  were 
given  over  to  the  vegetative  processes,  the  days  to  action  in 
the  motor  mechanism.  Having  nothing  to  do  at  night,  they 
went  to  bed.  There  was  no  other  place  to  go.  With  no 
electric  light  to  switch  on,  the  wires  to  and  from  the  highest 
brain  centers  were  switched  off.  Sleep  became  a  habit.  It 
worked  like  a  conditioned  reflex,  sunset  setting  it  off.  Even 
to-day,  some  find  it  hard  to  break  the  habit;  they  go  to  bed 
with  the  chickens  and  are  up  with  the  dawn. 




Judging  from  their  behavior,  all  our  four-footed  friends 
dream.  Presumably  their  dreams  are  as  unique  as  are  their 
individual  selves.  I  find  no  explanation  for  my  dreams  that 
does  not  take  stock  of  my  experience.  Dreams  themselves 
are  no  more  mysterious  than  is  any  other  phase  of  adjust- 
ment. Dreams  and  sleep  are  processes  of  adjustment  based 
on  physiological  processes. 

It  is  assumed  that  dreams  have  a  biologic  function.  "It  is 
the  dream  that  really  keeps  us  asleep,"  says  Humphreys.  He 
cites  the  sleeper  and  a  lawn-mower  outside.  The  sleeper 
dreams  he  hears  something  else:  if  he  "heard"  lawn-moiver, 
he  would  have  to  get  up  and  go  to  work.  "He  can  only  con- 
sistently go  to  sleep  by  hearing  noise  as  something  else  than 
the  sound  of  a  lawn-mower." 

That  explanation  is  too  simple;  it  covers  too  much  ground. 
True,  many  dreams  seem  to  have  the  function  of  guarding 
sleep.  But  to  say  that  the  dream  keeps  us  asleep  is  as  lucid 
as  to  say  that  sleep  causes  dreams. 

There  are  dreams  and  dreams,  and  sleep  and  sleep.  Some 
animals  and  people  are  always  dreaming;  some  seem  never 
more  than  half  awake.  But  inherent  in  life  and  human 
beings  is  the  necessity  to  "come  to"  when  life  is  imperilled. 

When  now  I  lay  me  down  to  sleep,  what  do  I  lay  down? 
Obviously,  not  the  same  body  that  I  carry  to  a  Harvard- Yale 
football  game.  But  the  body  that  carries  me  to  the  game  may 
be  any  one  of  80,000  bodies  in  the  Bowl.  When  half  of  them 
groan  the  other  half  cheer.  One  particular  body  may  sob, 
another  go  into  a  frenzy  of  delight;  another  may  yawn  and 
say,  "What  a  rotten  game!" 

The  body  I  lay  down  may  be  so  tired  it  is  "dead  to  the 
world"  and  beyond  stimulus  of  smoke,  though  my  own  bed- 
clothes are  on  fire  from  my  cigarette.  I  do  not  come  to  until 
fire  stimulates  my  skin.  No  dream  kept  me  asleep,  nor  did 
nightmare  arouse  me. 



I  may  be  very  tired  and  yet  wake  at  the  low  gentle  gnawing 
of  a  mouse.  I  curse  the  mouse  and  try  to  go  to  sleep  again. 
Why  could  I  not  have  dreamed  of  squirrels  in  the  wood 
gnawing  nuts  and  have  slept  peacefully  on? 

I  have  worked  late  and  am  tired.  I  must  be  up  and  at 
work  again  within  five  hours:  I  need  every  minute  of  my 
sleep.  I  drop  asleep,  and  come  to  with  a  start.  I  have  had  a 
horrible  nightmare.  I  can  sleep  no  more  that  night.  I  can 
discover  no  excuse  for  my  nightmare:  no  fire,  no  mouse, 
everything  quiet. 

No  excuse. 

I  sit  in  my  chair  on  deck  in  the  sun:  not  asleep,  not  think- 
ing, not  daydreaming.  "Without  a  thought  in  my  head."  I 
feel  that  I  could  sit  there  forever,  the  day  is  so  fine.  Sud- 
denly I  am  up  and  off.  I  go  to  my  cabin  and  write  for  hours. 
I  do  not  hear  the  dinner  gong.  The  steward  brings  hot  water; 
I  do  not  notice  him.  He  now  knocks  twice  before  I  hear 
him:  "Not  going  in  for  dinner?" 

I  may  know,  I  may  not  know,  what  brought  me  up  out 
of  my  chair  and  started  me  to  work.  But  when  because  of 
drugs,  alcohol,  or  toxins,  we  are  quite  beyond  reach  of  mes- 
sages from  without  or  from  within,  we  have  passed  out.  But, 
as  a  rule,  we  are  as  little  conscious  why  a  particular  thing 
pops  into  our  head  as  why  we  have  a  dreamless  sleep,  or  a 
silly,  lascivious,  or  nightmare  dream. 

Sleep  is  primarily  relaxation — general  dropping  off  of 
the  motor  mechanism.  But  activity  keeps  on,  though  slowed 
down  a  trifle,  in  the  digestive,  respiratory,  and  circulatory 
systems.  The  bodily  functions  continue;  the  motor  mecha- 
nism goes  out  of  action,  including  external  receptors  for  out- 
side stimuli.  Consciousness  quits,  the  mind  stays  on  the 
job.  Consciousness  is  a  functioning  of  arcs  of  the  cortex  of 
the  brain,  where  knowledge  is  stored  and  sorted.  When  cer- 
tain parts  of  the  cortex  are  injured — by  disease  or  wound — 
we  lose  control  of  something,  as  though  we  had  quite  for- 
gotten.   It  may  be  use  of  part  of  the  motor  mechanism,  or 



the  speech  mechanism,  etc.  But  with  the  cortex  out  of  action, 
we  forget  what  we  have  learned. 

Roused  from  deep  sleep  with  the  porter's  admonition: 
"Gotta  get  outa  here  in  five  minutes,"  we  make  a  mess  of 
dressing.  Seems  as  though  we  have  forgotten  which  shoe 
goes  on  which  foot,  and  we  blink  at  collar  and  tie  as  though 
we  had  never  seen  such  things.  We  are  not  "in  possession 
of  all  our  faculties." 

Hence,  dreams  mix  things  up.  The  right  shoe  on  the  left 
foot.  A  shirt  means  nothing.  And  we  wake  up  the  next 
morning  with  the  "funniest  dream;  can't  make  head  or  tail 
of  it." 

Or,  the  nightmare  wakes  us  up  and  finds  us  in  a  cold 
sweat.  Nightmare  behavior  is  jumpy  behavior.  The  child 
terrified  at  dusk  by  goblins  and  ghosts  and  Red  Riding-Hood 
wolves,  carries  an  easily  terrified  body  to  bed  and  may  carry 
it  for  eighty-odd  years:  jumps  at  every  sound  while  awake 
and  in  sleep  is  subject  to  nightmare.  Such  a  body  is  always 
prepared  to  jump,  until  its  hypersensitivity  is  educated  out 
of  it.  This  is  not  an  easy  process  if  the  early  fears  have 
been  branded  in. 

A  dream  may  be  anything.  If  A's  dreams  are  wish- fulfill- 
ments, A  apparently  is  a  Spanish-castle-builder  and  keeps  at 
it  in  his  dreams.  If  A's  dreams  are  also  sex,  it  is  because 
A's  mind  dwells  on  sex.  As  wishes  and  sex  enter  into  many 
lives,  they  are  likely  to  enter  many  dreams. 

Sometimes  the  frankness  of  our  dreams  amazes  us.  Life 
is  frank.  With  the  cortex  out  of  action,  we  lose  the  guardian 
of  our  morals.  The  mind  of  the  dreamer  rambles  around 
aimlessly  and  shamelessly.  For  the  same  reason  scientists 
often  solve  problems  in  chemistry,  mathematics,  etc.,  in 
dreams;  their  mind  was  free  from  inhibitions,  it  was  not 
afraid  to  try  out  new  combinations. 

We  solve  many  different  problems  of  conflict  just  before 
we  drop  asleep,  or  we  drive  them  from  our  head  long  enough 
to  fall  asleep.    That  problem  is  likely  to  form  the  subject 



of  our  dream:  the  body  mind  carries  it  on  from  the  point 
where  it  was  dropped  by  the  conscious  mind. 

Children  and  morons  do  not  solve  problems  in  chemistry 
in  their  dreams.  As  in  waking  states,  they  deal  with  the 
simple  affairs  of  the  day  or  of  yesterday.  Adults'  dreams 
may  drop  into  childhood  imagery  and  symbols.  Starting 
with  some  unsolved  problem  or  conflict  of  the  day,  the  mind 
drops  into  earlier  levels  of  mental  functioning.  Few  of  us 
go  through  the  day  without  some  early  memory  rising  up 
like  a  ghost  or  blissful  experience  to  haunt  us  or  make  us 
sigh  for  the  barefoot  days.  In  sleep  the  mind  wanders,  and 
easily  and  naturally  into  childish  things  or  into  childish 
methods  of  playing  cars  with  four  chairs,  one  dog,  one  cat, 
two  dolls,  and  Johnny  for  engineer  and  Mamie  for  conductor. 

"My  dream  has  come  true!"  Often  they  do.  As  I  write, 
my  body's  mind  wanders  fore  and  aft  and  up  and  down. 
It  will  be  surprising  if  it  can  anticipate  nothing  of  my 
behavior  or  my  family's  behavior  to-morrow  or  next  week. 
When  our  dreams  do  not  come  true — and  generally  they  do 
not,  for  truth  has  little  interest  for  dreams — ^we  say  nothing 
about  it. 

"Prophecy  lies  in  my  name,  saying:  I  have  dreamed,  I 
have  dreamed." 


We  land  at  Bombay,  deposit  our  belongings  at  the  hotel, 
and  start  out  to  see  the  sights.  We  need  not  move  a  foot: 
there  are  sights  all  around  us.  All  is  new;  nothing  seems 
like  home.  The  very  atmosphere  has  a  peculiar  odor,  a 
different  feel.  The  sun  is  not  the  same.  The  houses,  trees, 
birds,  shops,  signs,  noises,  voices,  cries,  cattle,  carts,  car- 
riages, trams,  are  different.  Swarms  of  human  beings  unlike 
any  that  we  know;  different  in  face,  build,  gait,  dress, 
coiffure,  foot  and  head  gear,  and  personal  adornment. 

Bombay  is  a  new  world.  Nothing  in  our  past  experience 
has  prepared  us  for  it.    Suppose  we  have  come  to  settle 



down  in  Bombay?  We  realize  that  we  have  much  to  learn — 
more  than  we  can  realize  at  first.  We  do  not  know  how  to 
act.  Wliy  does  that  man  stare  at  me  that  way?  What  is 
the  meaning  of  such  behavior?  We  have  no  ready-made 
behavior  by  which  we  can  adjust  ourselves  to  their  behavior. 

Even  the  flies,  bugs,  and  insects  are  difl"erent.  How  are 
we  to  know  which  are  harmful  or  dangerous?  At  the  edge 
of  a  park  we  meet  a  little  green  snake.  It  appears  harmless ; 
it  may  be  deadly  poisonous.    How  can  we  know? 

How  do  we?   How  do  we  know  the  world  outside  our  skin? 

We  enter  the  native  market.  Piles  of  strange  vegetables 
and  fruits.  But  nothing  that  we  know.  We  see  only  certain 
shapes,  sizes,  colors.  But  what  are  they  inside — sweet, 
bitter,  mushy,  hard,  juicy?  We  do  not  know  them.  Our 
mouth  does  not  water.  Suddenly  we  espy  a  box  of  peaches. 
Our  mouth  waters  now.  We  have  a  very  clear  knowledge 
of  peaches.  A  rat  runs  out;  we  jump  back.  We  have  not 
seen  a  rat  for  forty  years,  but  we  have  not  forgotten  rats;  nor 
that  a  rat  is  not  to  be  caught  with  the  bare  hands  as  a  rabbit 
may  be. 

The  first  rat  we  met  bit  us ;  the  first  rabbit  we  met  we  ate. 
I  know  more  now  about  rats  than  the  mere  fact  that  they  are 
ugly  and  are  to  be  killed  only  at  a  safe  distance;  and  about 
rabbits  than  that  they  are  harmless,  defenseless,  nice,  and 
good  to  eat.  But  there  was  a  time  when  "rat"  meant  no 
more  to  me  than  "hat";  or  "rabbit"  than  "Babbitt";  a  time 
when  neither  a  rat  nor  a  rabbit  meant  more  than  something 
which  could  stimulate  my  eye  and  provoke  my  reaching  for  it. 

Because  we  are  impelled  to  reach,  and  when  within  reach 
explore,  and  because  things  either  bite  us  or  we  bite  them, 
we  do  learn. 

The  world  we  know  is  the  world  we  explore  with  our 
fingers,  tongue,  eyes,  ears,  nose,  and  all  the  receptors  widi 
which  our  body  is  so  abundantly  supplied  on  or  in  die  surface 
or  within.  We  know  some  objects,  beings,  qualities,  and 
quantities,  well;  some,  not  so  well.    Included  in  this  knowl- 



edge  of  objects  are  attitudes  toward  objects.    We  learn 
eventually  to  let  sleeping  dogs  lie,  and  many  objects,  persons 
and  situations  alone. 
Don't  monkey  with  that! 

But  we  do.  There  is  more  monkey  than  rabbit  in  our 
inheritance.  As  a  result,  a  lively  boy  or  girl  of  fifteen  years 
knows  as  much  as  the  "average  American." 

'Ms  there  anything  that  child  does  not  want?"  asks  the 
harried  mother.  The  child  replies,  "Nothing."  And  the 
child  that  cries  till  he  gets  it  answers:  "Why  not?  Wliat  are 
things  for  if  I  am  not  to  be  allowed  to  examine  them?" 

It  is  a  slow,  complicated  process,  but  after  the  child  can 
walk  it  goes  on  at  an  astonishing  rate.  Tireless,  insatiable, 
indefatigable  youngsters!  "If  I  didn't  stop  them  they  would 
tear  down  the  house  and  burn  up  the  barn."  Why  not? 
They  might  build  a  better  one,  or  learn  a  new  culinary  art, 
as  Charles  Lamb  says  the  Chinese  learned  roast  pig. 

Here  is  a  baby.  It  has  learned  the  location  of  its  eyes, 
ears,  nose,  and  toes,  and  can  reach  and  grasp  and  handle. 
Assume  that  it  has  been  "carefully  guarded" — which  usually 
means  it  knows  next  to  nothing.  Offer  it  a  peach,  pin,  stick 
of  candy,  match,  red-hot  poker,  cat's  tail,  firecracker;  same 
reaction:  baby  wants  it.  It  may  learn  enough  in  one  lesson 
to  alter  its  behavior  thereafter  to  each  of  these  objects.  Why? 
Because  hot  pokers,  firecrackers,  cats'  tails,  pins,  candy,  etc., 
have  their  own  behavior.  Sooner  or  later  baby  learns  that 
the  tail  of  a  cat  is  not  a  handle  to  a  plaything. 

The  first  peach  baby  meets  is,  let  us  say,  through  the  eyes. 
Mere  visual  stimulus  was  enough  for  the  first  lesson.  The 
peach  did  not  explode  or  bite  or  burn.  Baby  explores 
further.  Peach  can  also  stimulate  the  skin  of  hand  or  body 
or  face;  also  the  nose,  the  tongue,  and  sense  organs  in  the 
alimentary  canal  and  kinesthetic  senses.  By  the  time  the 
exploration  is  complete  the  child  knows  a  peach.  Through 
the  responses  to  the  many  diverse  stimuli  a  peach  can  make, 



the  child  knows  more  or  less  of  its  color,  shape,  weight, 
hardness,  odor,  taste.  That  it  has  a  skin,  that  the  skin  is 
tough  and  covered  with  down,  that  the  down  is  unpleasant 
to  skin  of  hands,  face,  mouth,